FM 4-126 Antiaircraft Artillery Field Manual: Service Of The Piece 90-MM Antiaircraft Gun On M1A1 Mount, 1943

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RESTRICTED

WAR DEPARTMENT

ANTIAIRCRAFT ARTILLERY
FIELD MANUAL

SERVICE OF THE PIECE
90-MM ANTIAIRCRAFT GUN
ON MlAl MOUNT

25 OCTOBER 1943

OCT(

THE U

BEARY

mm 411301

If KWm, KEE'i

S'^fft A fe^^^f fi^j H

Dissemination of restricted matter. — The information contained in re-
stricted documents and the essential characteristics of restricted material
may be given to any person known to be in the service of the United States
and to persons of undoubted loyalty and discretion who are cooperating in
Government work, but will not be communicated to the public or to the press
except by authorized military public relations agencies. (See also par. 186,
Alt 380-5, 28 Sep 1942.)

RESTRICTED
FIELD MANUAL

FM 4-126

JS SERVICE OF THE PKCE
90-MM ANTIAIRCRAFT GUN ON MlAl MOUNT

Changes
No. 4

WAR DEPARTMENT
Washington's, D. C, 28 June 1946

FM 4-126, 25 October 1943, is changed as follows:
22.1. TARGET, VT FUZE (Added). When ordered to engage
using VT ammunition, the gun drill described in para-graph 22
will be as follows:

GC commands, TARGET, VT TITZE. •

G, 2, 5, 7, 8, 9, 10, 11, 12 perform duties as presci^ibed in Anti-
aircraft Artillery -Drill.

1 takes round from 6, who has received it from 8, and relays
^it~tiJ~4~(~l~h£L'nds round to 4 with left hand under rear of round
and right hanxi on fuze. (See fig. 17).)

3 stands by ready to function in the event mechanical time
f u^e_ajiim unition is subsequently ordered:

4 holds round at loading position a;t the breech where G can
ram it home; as soon as round has been loaded, steps back
with right foot and stands ready to receive next round from
1; continues loading until CEASE FIRING is given or the
prescribed number of rounds has-been fired.

6 relays ammunition to 1.

AC supervises ammunition^ squad ".and- the:,.rfiplenishing of am-
munition at gun position. '

Caution. VT fuzes must not he inserted in the fuze
setter.

23. FIRE (As changed by C2) (Superseded).
GC at command FIRE, repeats command for 'first round" only,
succeeding rounds being fired without further command;
if a limited number of rounds has been prescribed, he cau-
tions ''(So niany) rounds only."
4 removes round from fuze setter and holds'it at loading posi-
tion-at -the-breech where G can ram it home; as soon as

AGO 7D— July 705552°— 46 1

round has been loaded, pivots on right foot, steps back with^
. left, and stands ready to remove next round from fuze'
setter; continues loading until CEASE FIRING is given or'
^ the prescribed number of rounds has been firedo
, G when 4 places round in breech, rams round ''home" with^
front of his left clenched fist; when his fist is knocked clear
by the rising breechblock, pivots back on his right foot and
fi-es gun; continues. ramming and firing until CEASE FIR-
ING is given, or the prescribed number of rounds has been
fired; kicks empty cartridge cases clear of platform; in case
of misfire, calls "Misfire" to GC and keeps all cannoneers
clear while the prescribed safety precautions are taken,
(See paro 40.)
5' continues to match pointers on fuze- setter.

1 continues to load fuze setter; trips release lever and keeps
pressure on base of round as each round is set.

'3, turns fuze setter, setting crank each time release lever is
tripped by 1; calls ''Set" each time setting crank hits stop,

2 continues to, watch elevation lagmeter pointer, or, if opera=
ting gun manually, continues to match pointers.

7 continues to watch azimuth lagmeter pointer or, if operating

c , gun manually, continues to match pointers.
6, 8 continue to relay ammunition to 1.

9 , clears away empty shell cases from gun emplacement, being

careful to avoid-getting behind gun when it is in action.
10, 11, 12 maintain ammunition supply under supervision of AC»
AC supervises ammunition squad.^

26o TARGET, DIRECT FIRE (Superseded).

GC commands: TARGET, DIRECT FIRE; designates target
and sights along gun tube to. assist azimuth and elevation
setters to point the gun,

2, with handwheels engaged and transfer valve plunger in the
OUT position, sights through elevation telescope and
operates gun manually to get target on proper range line;
, xalls ^^ON'^ when he is on target. v

7j with handwheels' engaged and transfer valve plunger in the
OUT position, sights through azimuiii telescope and. oper-
ates gun manually to get target on proper deflection, hne;
calls /'On" when he is on target, ,

G _ opens breech by bearing down pn breech operating handle^
returns breech operating handle to latched position; after 4

AGO 7D

^ places round in breech, rams round home with front of left
clenched fist; watches GC for signal to fire. ,

'4 receives round from 1 and holds it in the loading position at
the breech where G can ram it ''home," as soon as round has

J been loaded, steps back to receive the next round from 1.
1 relays ammunition to 4.

6 relays ammunition to 1. "

8 relays ammunition to 6.

3 takes post about 5 yards away from gun, at right of eleva-
tion setter, to observe and spot bursts.

5 takes post about 5 yards away from gun, at left of azimuth
setter, to observe and spot bursts.

9 removes protective covers from ammunition stacks and
makes ammunition available to 8.

54. 90.MM GUN Ml ON MOUNT MlAl (as added by CI).
Items number 21, 30, 31, 32, 33, 52, and 53 are rescinded.

56. DAILY MAINTENANCE CHECK LIST (as added by CI).
Item number 21 is rescinded.

57. WEEKLY MAINTENANCE CHECK LIST (as added by Cl).
Items number 30, 31, 32, and 33 are rescinded.

58. MONTHLY MAINTENANCE CHECK LIST (as added by
01).

Items number 52 and 53 are rescinded.

[AG 300.7 (19 Jun46)].

By order of the Secretary of War:

Official:

EDWARD F. WITSELL
Major General
o The Adjutant General

Distribution:

AAF (10); AGF (40); T (2); HD (2); USMA (50); A (2);
CHQ (2) ; B 4, 44 (5) ; R 4, 44 (5) ; SBn- 44 (5) ; Bn 44. (5) ;
T/0 & E 4.-15 (40).; 4^66 (5); 4-77 (10) ; 44-115 (40);
Special distribution.

For explanation of distribution formula, see FM 21-6.

DWIGHT D. EISENHOWER
Chief of Staff

AGO 7D

U.S.

GOVERNMENT PRINTING OFFICEi

I94S

FM 4-126
C 3

RESTRICTED

ANTIAIRCRAFT ARTILLERY FIELD MANUAL

SERVICE OF THE PIECE, 90-MM ANTIAUtCRAFT GUN
ON Ml Al MOUNT

Changes ) WAR DEPARTMENT

No. 3 I Washington 25, D. C, 19 March 1945

FM 4-126, 25 October 1943, is changed as follows : %

CHAPTER 3

DRILL PROCEDURES
» ♦ ♦ * ♦

Section VII (Added)

INDIRECT GROUND FIRING DRILL

N^"^ 29.1 Orientation.— In preparing the battery for indirect
-md firing the procedures below are followed :
/. Guns are emplaced, leveled, and oriented at 200 mils eleva-
tion. (Special attention must be given to preve^t^jiimp and
shifting of gun due to low-angle fire.)

Hj). Azimuth sights M24 are installed and coUimated at the most
distant range possible,

c. The battery executive officer sets up the aiming circle over
battery executive's stake (stake about 30 yards in front of gun
line). When aiming circle is oriented, the executive j)oints it at
the giin azimuth sight and the azimuth setter sights on aiming
circle.

d. Executive calls off back azimuth of aiming circle and azi-
muth setter sets reading on mechanical dial by means of toothed
wheel in azimuth indicator regulator. This setting is checked
by having the gun commander boresight on aiming circle while
the executive points aiming circle at gun tube. The reading at
the gun and the back azimuth of the aiming circle should agree.

€. After the gun is oriented it is traversed to some even azi-
fliuth in the center of the field of fire. Two poles are placed in
line,, one about 60 yards and the other about 70 yards in front
of tlie azimuth scope. If the poles are properly placed the azi-
AG0 311D— Mar. 622804''— 45

mutli setter will see only one pole when looking through th^
«icope„ The even azimuth is marked on the gun and is used as a
rapid orientation check during' firing, A third pole is placed at
a distance of approximately 60 yards in front of and in line with
the axis of the gun tube.

Note,— The purpose of the two poles for the azimuth sight is
to check any lateral shift of the gun. The purpose of the third
, pole for the gun tube is to check that the sight has stayed in
collimatiotto J ^ ^

: B 29,2 FiBE Commands.—^. Fire commands to each gun in an
indirect ground firing role come from the battery executive.
His normal position during firing is at a point where he can be
heard (voice control) by all guns. He is assisted by a phone
operator, the phone wire being long enough to facilitate any
necessary movement from gun to gun. He is also assisted by a
recorder who records each command as given by him. Fire
commands originate at the AAA FDC and are relayed by phone
to the battery executive. The battery executive's phooe !o a
direct line from the FDC, NOT TO THE OUNS,

6. Upon moving into a tactical position, the -executive reports
the following to FDC : ^

(1) ■ Battery oriented and ready to fire. ^V^^

(2) Minimum eleva.tion.

(3) Base piece (Gun No. ) and dista^ce from DP in yards.

(4) Width of battery front in yards.

(5) Ammeoitlon (type and amount) on hand.

c. The sequence of commands given by the battery executive
' to the guns Is as follows :

(1) Type of adjustment, such as: BATTERY ADJUST or
GUN MOo AB JUST.

(2) Projectile, such as : SHELL HE

(3) Fu5se, such as: FUZE M43A3 or FUZE PD M48.

(4) Fuze setting, such as: TIME 11.1; BELAY; QUICK.

(5) Azimuth, such as: AZIMUTH (SO MUCH).

(6) Pieces to fire, such as: BATTERY or GUN Noc

(7) Method of fire, such as RIGHT (LEFT); (SO MANY)
ROUNBS^ or BY PIECE AT MY COMMANB,

(8) QUABRANT (SO MUCH) or ELEVATION (SO
MUCH)„ If the command QUABRANT (SO MUCH) is given
the QE Is set on the gun with the gunner's quadrant. If, how*
ever, the command ELEVATION (SO 'MUCH) is given, the

^ AG0 311D*

QE setting is set with the elevation indicator regulator mechan-
ifal dials. ^

. NoTF —Changes in azimuth, fuze, number of rounds to be fired
are amiouncef as needed. If they are not repeated there is no
cMnge from the last command. The word "^z^^IJ*^" ^
repeated with each new azimuth. The word "Quadrant or
'Sation,'' once given, need not be repeated ^j^rmg any one
problem. Gunner's quadrant settings are normally used during
registrations.

a ON No. , CLOSE (or OPEN) . The battery

executive receives this command from the AAA FDC and aided
by his recorder— computes the azimuth for each gun. He then
calls each azimuth individually to each gun. The object is to
converge or widen the sheaf. For example :

(1) The command received by the executive from the FDC
being— AZIMUTH 4380, ON No. 1, CLOSE 2, the commands to

_the guns are :

AZIMUTHNo. 1, 4380
AZIMUTH No. 2, 4382 (2 mils)

AZIMUTH No. 3, 4384 (2 mils for No. 3 and 2 mils for
No. 2)

AZIMUTH No. 4, 4386 (2 mils for No. 2, 2 mils for
No. 3, and 2 mils for No. 4)

(2) If a center gun was used to close, the command received
by the executive from the FDC might b^AZIMUTH 4380,
ON No. 2, CLOSE 2, the commands to the guns are :

AZIMUTH No. 1, 4378
AZIMUTH No. 2, 4380
AZIMUTH No. 3, 4382
AZIMUTH No. 4, 4384

B 29.3 Drill

GC at command BATTERY ADJUST or GUN NUM-
BER ADJUST, repeats the command— sees that all

personnel take post on the run if not already at posts-
places carrying strap of gunner's quadrant case over his
- shoulder. Takes position on gun platform to left rear of 2.

Other positions are the same for AA drill.
G opens breech by bearing down on breech operating handle
until breech block is locked open— returns breech operating
handle to latched position and then sees that breech operat-
ing cam lever is set for "Automatic." . '

AG0 311D

AC at mmmam for type of projectile and fuze, sees that am'
™»m„B sa„ad secwes the required .monnTTnTtZ

■i type ammunition. F^^F^i
10, 11, 12 relay ammunition to 1

IS IS set witls proper tool.
4 and 0" load a§ ie AA ire

^ .™rrT'' , turns azimBth hand crank

Stl r™^'*"' ^^^''^ maintains this

n~d ' ^ - an-

■ ?r J « !"l*.r* '''^ '^"h the words

toe of fflre" at the bottom and the arrow pointing toward

rZ i..,T ! . tJ'^ °f the qnad-

axis of the bore. It is Important that ©c take the same

tered-reports, ^^r' The last movement o£ the "

When the babble is approaching the center, in order that
the final entering may be performed accnrately.

■ Ste rrd tL ? r""" ^^^^l^'^-- "mechanical

when the gnn fg loaded. 7 has reported ''itaKfrwrTn'd
2 has reported ,^r, reports, ^ 00

<S0, as soon m ® reiaort^ "'/SE^^sA/* i.,^^- 7 '^"^U to »C.
mutr mJ^l , indicates .to the execntive

that the pieee is ready to fire by raising his right arm

vertically. When the executive cannot see the arm signal,

GC reports verbally to the executive, **No. , readif*,

GC, when executive gives the command to iire, drops his right
arm smartly to his side. When G cannot see his arm

signals, GC commands : No. , FIKE.

G fires at the command of GC.

GC when firing is completed, reports to executive officer,

*Wo. Gun fired rounds".

GC at command: CEASE EIBIHG, END OF MISSION (or
BEGISTHATION), commands: CHECK ORIENTA-
TION— When orientation is correct, commands: BEST.
[AG 300.7 (15 Mar 45)]

By order of the Secretary of War :

Official :

J. A. ULIO

Major General

The Adjutant General

G. O. MARSHALL
Chief of Staff . _

Distribution :

AAF (10) ; AGF (40) ; ASF (2) ; T of Opns (2) ; Arm & Sv
Bd 44 (2) ; Def Comd (2) ; HD (2) ; Sch 4 (25) ; 44 ( 250) ;
USMA (50) ; Tng C 44 (50) ; A (2) ; CHQ (2) ; B 4, 4.4
(5) • R 4, 44 (5) ; B.n 4, 44 (5). T/O & E: 4-66 (5) ;
4-77 (10) ; 44-15 (40) ; 44-115 (40).

Refer to FM 21-6 for explanation of distribution formula.

AGO 311D

U. S. GOVERNMENT PRINTING OFFICE: 1945

RESTRICTED

EM 4-126

c 2

ANTIAIRCRAFT ARTILLERY FIELD MANUAL

SERVICE OF THE PIECE 90~MM ANTIAIIlCilAFT GUN
ON MlAl MOUNT

Changes 1 WAR DEPARTMENT,

No. 2 J Washington 25, D. C, 14 September 1944.

FM 4-126. 25 October 1943, is changed as follows :

■ 6. Instructions.

* « * * . «
(Page 4)

Note (Added). — To provide fm^ battle emergencies all men
of the gun section must be trained in the duties of the other
members so that a rapid shift of personnel is possible. In ad-
dition, battery personnel not assigned specific duties during
firing, such as truck drivers, clerks, cooks, etc., must be trained
in the fundamentals of the drill so that, if necessary, they can
be used as replacements.

■ 13. EMPLACEMENT OF GUN WITHOUT PRIME MOVER.

* * * * 4:

"(Page 10)

5 removes equilibraror piston stop from equilibrator and in-
serts in holder on top of equilibrator cylinder.

Note (Added). — Most guns have a protective wooden ''dough-
nut" in the equilibrator cylinder, and the equilibrator piston
stop is not supplied or used.

1, 3, 5, 7 extend and pin left outrigger

* * * * ip

(Page 12)

5, 6, 7, 8 at rear outrigger assist in crushing mount by pulling
up on rear outrigger to center gun over wheels.

* * ❖ * *
Note.— //^ COUNTERPOISE CYLINDER RODS ARE NOT

RETRACTED FAR ENOUGH TO PERMIT PUTTING THE
GEAR BOXES IN PLACE, THE MOUNT MUST BE CRUSHED
FURTHER BY SEVERAL MEN STANDING ON EACH SIDE
OUTRIGGER TO INCREASE THE DOWNWARD FORCE.

AG0 318D 598804''— 44

ANTIAIRCRAFT ARTILLER'K FIELD MANUAL

1, 2 loosen locking - * * to loosening them.

1, 6 with gun tube horizontal, place wrench on gun jack screw
and jack gun out of battery approximately 2 inches; re-»
tract gun jack screw and note whether the breech ring re-
mains in contact with the gun jack screw. Caution: RE-
TURN JACK SCREW TO ITS REARMOST POSITION
AFTER TEST. If it does not, the oil reserve and gas
pressure must be checked before proceeding with the
emplacement.

2 elevates gun to maximum.

3, 4, 7, 8 crank bogie down until the pedestal rests on the
ground.

5, 6 place fuze setter * * * fuze setter junction box.

]|C * * , * *

(Page 14)

G moves trail lock * * * trail is low^ered.

Note.— It may be necessary to dig out under entire length of
trail to permit it to be locked in lower position. The trail must
not contact the ground until it is locked in its lower position.

4c * * * *

(Page 15)

G tightens auxiliary leveling screw by screwing it down as soon
as the mount has been leveled.

Note (Added). — The gun tube should he horizontal over the
trail to facilitate this tightening operation.
GC verifies leveling of mount.

* si! * * *

■ 14. EMPLACEMENT OF GUN USING PRIME MOVER.

* Jfr * * *

(Page 18)

G, 1 unpin traveling lock brace, lower traveling lock, and pin it
to the trail.

1, 6 with gun tube horizontal, place wrench on gun jack screw
aiid jack gun out of battery approximately 2 inches; re-
tract gun jack screw and note whether the breech ring re-v
mains in contact with the gun jack screw. If it does not,

2 AG0 318D

90-MM ANTIAIRCRAFT GUN ON MlAl

V the oil reserve and gas pressure must be .checked before
proceeding" with the emplacement.

2 elevates gun to maximum.

(Page 19) '

7, 8 crank bogie down until the pedestal rests on the ground.
3, 4 assist 7, 8 crank bogie down.

* :j: . ❖ * *

G moves trail lock * * * the swing bolt:

Note. — It may he necessary to dig out under entire length of
trail to permit it to he locked in the lower position. The trail
must not contact the ground until it is locked in its lower posi-
tion,

* * ' ' 5s >:-. 4t

(Page 20)

G tightens auxiliary leveling screw by screwing it down as soon
as the gun has been leveled.

Note (Added). — The gun tuhe should he horizontal over the
trail to facilitate this tightening operation.
GC verifies level of gun.

* ❖ * * 4( .

■ 15. MARCH ORDER WITHOUT PRIME MOVER,

* * . * . * . *
(Page 21)

5, 6 remove fuze setter from its firing position and put it in .
traveling bracket. Place fuze setter seat in traveling posi-
tion.

(Page 22)

5 removes the equilibrator * * piston stop pin.

2, 4, 6, 8 put right platform * * * it in position.

* * . . ❖ • ,* *

■ 16. MARCH ORDER USING PRIME MOVER.

* ■ . * )it
(Page 25) :

5, 6 remove fuze setter from its firing position, and put it in
^traveling bracket. Place fuze setter seat in traveling posi-
tion.

* * * * ' «
AG0 318D 3

ANTIAIRCRAFT ARTILLERY FIELD MANUAL
(Page 26)

1, 2 with the trail * * * bogie securing bolts.

G, 1, 2, 3, and 4 at trail and 5, 6, 7, and 8 at rear outrigger

tip the mount g'ently forward on the trail.
5, 6, 7, and 8 break rear outrigger at its outer joint.
G, 1 raise traveling lock brace.

* * * . * 4(

(Page 27)

3, 4, 5, 6, 7j 8 extend and pin the rear outrigger.
GC directs prime mover to back up to couple mount.

* * * * *

G plugs electric brake cable into prime mover and connects

breakaway chain,
1, 2, 4, 7, 8 place rear outrigger in traveling position.

*****
G pulls out on latch * * * as it will go.
5, 6 put canvas covers on counterpoise cylinders.

*****

■ 17. EXAMINE GUN.

*****
(Page 29)

3 assists 5 in examining, * * * in fuze setter.
7 checks oil level * * * oil if necessary.

*****
(Page 30)

7 manually traverses gun * * * no excessive backlash.
1, 6 with gun at zero elevation, place wrench on gun jack screw
and jack gun out of battery approximately 2 inches ; retract
gun jack screw about 1/4 inch and note whether the breech
ring remains in contact with the gun jack screw. Caution:
RETURN JACK SCREW TO ITS REARMOST POSITION
AFTER TEST. If gun does not maintain contact with gun
jack screw, notify GC who then commands: CHECK RE-
COIL SYSTEM.

1, 6 with gun still at zero elevation, remove oil filling
plug— insert liquid release tool and bleed off oil re-
serve—connect screw filler, and reestablish oil reserve —
remove screw filler and connections with replace oil
filling plug. w

AGO 318D

90-MM ANTIAIRCRAFT GUN ON MlAl

Note r IF NO OIL RESERVE IS PRESENT IT IS
NECESSARY TO FILL THE RECOIL CYLINDER BE-
FORE REESTABLISHING AN OIL RESERVE!, NEVER
ADD TO AN EXISTING RESERVE.
1, 6 charge gas pressure into recuperator cylinder to 830
pounds per square inch. If the gun still fails to return
as the screw is retracted— CAI*L QUALIFIED PER-
SONNEL TO REMEDY THE TROUBLE.
2, if gun returns as gun jack screw is retracted with gun at
zero elevation, elevates gun to maximum elevation. Cleans
and oils elevating rack. Caution: UNDER SANDY OR
DUSTY CONDITIONS, ELEVATION RACK SHOULD BE
CLEANED, OILED AND WIPED DRY.
1, 6, retract gun jack screw completely tb original position.
If gun fails to return to battery, direct 2 to depress gun
slowly. If gun does not return to battery by the time it has
been depressed to 710 mils, notify G-C who .then commands:
CHECK RECOIL SYSTEM.

This check is performed as outlined in the preceding step.
If this check was already performed in preceding step, or
if after checking, the gun still fails to return to battery
by the time it is depressed to. 710 mils, CALL QUALI-
FIED PERSONNEL TO REMEDY THE TROUBLE.

Note : In addition to the tests as may be required in
EXAMINE GUN, the recoil system is checked at such in-
tervals as are determined by the battery commander,
2 depresses gun at direction of 1 or 6 to determine if gas
pressure in recuperator is sufficient. Then elevates and
depresses (gun should elevate and depress with equal ef¥ort) ;
with 7 examines gun junction box.

7 with 2, examines gun junction box;

* , * ❖ *

■^19. CHECK ORIENTATION.

4( . * ili *

(P'age 31)

8 places vertical and horizontal cross hairs across muzzle of
gun.

,* * * * *

G sights through hole in breechblock bushing and lines up ver-
tical and horizontal cross hairs on muzzle with * * *

on orienting point.
AGO 318D 5

ANTIAIRCRAFT ARTILLERY FIELD MANUAL

2 elevates or depresses gun as directed by G.

7 traverses gun right * * * adjustment can be made.

(Page 32)

Caution: Never, attempt to zero lagmeter mechanically while
data transmission system is energized.

GC commands o CHECK ALIGNMENT.
7 checks alignment of azimuth direct-fire sight.
2 checks alignment of elevation direct-fire sight.
G checks sighting of gun and replaces firing mechanism in
breechblock.

GC commands : CHECK ELEVATION ORIENTATION.

* * « * m

2 elevates gun until G calls, "Hold"; * * * {a small screw
cover must be removed before this adjustment can be made).

* * * * *

■ 20. CHECK SYNCHRONIZATION.

(Page 34)

GC commands: CHECK SYNCHRONIZATION.

2 sees that transfer valve plunger is OUT; sets selector switch
on elevation indicator on AUTOMATIC.

7 sees that motor switch is OFF at gun junction box and that
transfer valve plunger is OUT ; sets selector switch on azimuth
indicator on AUTOMATIC.

GC verifies that selector switches are on AUTOMATIC, and
transfer valves are OUT; notifies range officer that gun is
ready for power, after power is applied and director pre-
pared, secures quadrant elevation, firing azimuth, and fuze
range values from range officer and gives the information to
2, 7, and 5, respectively.

Note (Added). — Power must he applied with regard to the
particular equipment combination being used. After the range
ofjficer has been notified that all guns are ready for power, he will
check the associated radar and director to see that they are
ready to receive power. When all equipment is ready, the range
officer directs the power plant operator to start generator and
idle until warm, set generator voltage to the minimum possible
by turning rheostat on power plant control panel clockwise to
stop, then close power plant switch to energize system, run

AGO 318D

90-MM ANTIAIRCRAFT GUN ON MlAl

generator speed up to 1,200 rpni, or 60 cycles depending on
generator used, and increase voltage hy means of the rheostat
until the voltage at director reads 115 volts. The voltage at the
power plant should noit he raised ahove 126.
2. raises sliding cover * * * gun junction box,

* * « * *
(Page 35)

GC checks oil level as switch on gun junction box is turned on ;
if oil level rises or disappears from the glass, orders niotor
turned off immediately and notifies qualified personnel.

* * H: * «

2 if lagmeter pointer is not at zero position, directs Gr to turn
adjusting screv^ on amplifier marked EL until lagmeter is
zeroed (this balances the amplifier).

7 if lagmeter pointer is not at zero position, directs G to turn
adjusting screw on amplifier marked AZ until lagmeter is
zeroed. (This balances the amplifier.)

* . * * , . - . *

S 23. FIRE.

H: * * . * «

(Page 39)

G without power rammer * * * safety precautions are
taken (see par. 40).'

Note (Added). — If hand ramming is used instead of the spring
rammer, the spring rammer should not he removed hut may he
made inoperaMve hy either of the two folloimng methods:

(1) Removal of rammer hook. This operation consists merely
of removing the upper rammer hook pin nut and lifting the hook
from the pivot pin. {See TM 9-1S70A.)

(2) Disengaging rammer hook from the plunger rack. By
use of a pinch har, force the rammer hook to the left away from
the plunger rack, therehy compressing the plunger spring and
disengaging the rammer hook from the rack. Spring tension
acting against the plunger rack forces the raek forward ahout

inch, preventing the rammer hook from reengaging the rack.
This operation will completely disengage the rammer hook from
the plunger rack, therehy allowing the gun to recoil and counter-
recoil without operating the spring rammer.

To save time in reengaging rammer hook with the phmger
rack and to prevent any danger of losing or misplacing removed
parts, the second method is more practical. After the rammer

AGO 318D

ANTIAIRCRAFT AltTILLERY FIELD MANUAL

hook has heen disengaged front the plunger rack J)y this method,
it COM J)e reengaged hy merely forcing the plunger rack rearward
1/4 inch, thereby allowing the rammer hook to reengage the rack.

5 continues to match pointers on fuze setter/

*****

■ 27. FIRE.

* * * * *
(Page 43)

5 spots bursts, calls ''Right (so many mils)", "Left (so many-
mils)", or "Hit", as the case may be.

* * * « . *

■ 36. Tracking. — Manual operation of * * * of the reticle.
The center of this reticle should always point ahead of a moving
target moving in azimuth, and at a stationary target. The
elevation setter ♦ * * estimated range line.

■ 37. Fire Control. — The gun commander « * * spotters
(3 and 5). Nos. 3 and 5 observe the bursts and call "Right
(so many mils)" or "Left (so many mils)" for the azimuth
observer and "Over" or "Short" for the range observer. For
a full discussion of fire control using direct-fire sights, see FM
44-10 (4-110) and FM 44-21 (4-121).

■ 40. General. — Safety precautions to be observed are pre-
scribed in AR 750-10 and TM 44-234 (4-234). The more im-
portant * * * under combat conditions.

[A. G. 300.7 (6 Sep 44).]

By order of the Secretary of War:

G. C. MARSHALL,
Official: Chief of Staff.

J. A. ULIO,

Major General,

The Adjutant General,
Distribution:

As prescribed in paragraph 9a, FM 21-6 except D14 (5),
AA Sch (500) ; T of Opns (5) ; Base Cs (5) ; Island Cs
(5) ; Def Cs (5), Sectors (5), Sub-sectors (5) ; Base Sec-
tors (5) ; HD (5) ; B44 (5) ; R44 (5) ; Bn44 (5) ; IG44
(15) ; AAATC (100) ; AARTC (100).

IC 44 : T/0 & E 44-17 ; 44-117.

For explanation of symbols, see FM 21-6.

8 AG0 318D

tJ. S. GOVERNMENT PRINTING OFFICE; 8944

PM 4-126

^ RESTRICTED °V

ANTIAIRCRAFT ARTILLERY FIELD MANUAL

&ERVICB OF THB PIECE, 90-MM ANTIAIRCRAFT GUN
ON MlAl MOUNT

Changes! WAR DEPARTMENT,

No. 1 J Washington 25, D. C, 21 August 1944.

FM 4-126, 25 October 1943 is changed as follows:
CHAPTER 7 (Added)

PREVENTIVE MAINTENANCE, 90-MM GUN Ml ON
MOUNT MlAl AND REMOTE CONTROL SYSTEM M2

Section I
GENERAL

■ 52. References. — For detailed information on maintenance
and adjustment of the Ml gun on the Ml Al mount, see TM 9-370;
and for Remote Control System M2, see TM 9-2642. For
lubrication, see War Department Lubrication Order No. 62.

■ 53. General Instructions. — Maintenance as discussed herein
is concerned only with first and second echelon maintenance.

a. First echelon maintenance is maintenance performed by the
operating personnel with tools supplied with the equipment.

6. Second echelon maintenance is performed by qualified bat-
tery specialists or men who have completed a recognized course of
instruction.

c. The maintenance lists following have been grouped into two
sections. Section II lists the . maintenance necessary for each
part and the references for more detailed instructions. Section
III has the information of section II in the form of ready check
lists.

d. The numbers of the items on the check lists correspond with
the numbers in section II to permit ready reference.

e. Symbols used herein are as follows: ''O,'^ operating per-
sonnel or those men who habitually work with the equipment:
"M," maintenance personnel of the battery (qualified techni-
cians); "D,'' daily items of maintenance; "W,'' weekly main-
tenance; and ''M,*' monthly maintenance.

AG0 439D 598704 44

Section II

DESCRIPTION OF MAINTENANCE ITEMS
■ 54. 90-MM Gun Ml on Mount MlAl.

Item

.1 Gun and assembly

2 Gun mount

3 Gun tube '_

4 Exposed recoil slides

5 Recoil mechanism

6 Recoil piston rod retainer.

7 Recoil valve • control bar fol=

lower screWo

Ech-
eloD

Mainte-
nance
crew

o
o
o

Inter-
val

D
D
D

Maintenance required

Note general appearance, and check for burs„
Check for tight nuts and bolts, and see
that all operating parts are Rubricated
properly and move freely.

Elevate and depress by hand between upper
and lower stops. Traverse 6400 m to
check freedom of movement. Report un-
due binding or backlash to Ordnance.

Clean and oil bore and chamber. After firing,
clean with sponging solution, oil with ap-
propriate seasonal lubricant.

Keep exposed surface coated with oil. Clean
and oil before firing. If atmosphere is
dusty, clean slides of all oil before firing.

Test oil reserve and gas pressure by the gun
jack method, replace oil reserve and add
nitrogen if necessary.

See that the piston rod retainer is screwed
tightly into the breech ring.

See that the recoil valve control bar follower
screw and its Jam nut at the rear of the
recoil valve control bar are tight.

>■ 8 Counterrecoil valve

o
o

4^ 9 Recoil throttling valve guides.

o 10 Counterrecoil buffer

11 Breechblock

12 Breech recess

13 Breech operating shaft gears.

14 Breech closing spring chain..
CO 15 Firing mechanism

16 Spline shaft.

17 Breechblock crank, chain

terminal crank and operat-
ing crank.

18 Equilibrator ...

Check to see that valve is functioning prop-
erly.

Lubricate as required.

Check oil level while gun is at zero degrees
and level, add oil if necessary. Note ac-
tion of buffer when gun is jacked out of
battery. Notify Ordnance in case of
leakage.

Disassemble, clean, and lubricate (also after
' firing). Check for burs, see that screw

heads are flush or below front and rear

surfaces. Check for smoothness of action.
Check for scoring and burs.
Clean and lubricate as required.
Clean and oil as necessary.
Disassemble, clean and oil. Check action

of sear on firing pin. Check action of

firing pin and see if pin protrudes beyond

breech block.
Check that spline shaft is fully seated, that

detent pin is home, and that shaft is flush

with crank arm.
Check that all cranks are properly in place

and operating smoothly,

Check for proper tension and adjust if nec-
essary. If maximum adjustment is
reached notify Ordnance. Clean and
lubricate cham. Check ^quilibrator for
dents.

Item

19 Elevating rack and pinion

20 Fuze setter

21 Power rammer

22 Auxiliary leveling screw. _

23 Direct fire sights

24 Miscellaneous

25 Gun and assembly. =

26 Recoil slides^

Ech-
elon

Mainte-
nance
crew

Maintenance required

Clean with solvent and lubricate lightly »

If firing in a dusty or gritty atmosphere,

wipe rack dry before firing.
Clean rings thoroughly. Lightly oil pawls

and guides. Lightly grease other surfaces.

Check orientation and synchronization.
See that rammer arm latches in vertical

position properly. Check oil in spring

rammer buffers. Also before firing.
Check to see that the screw is fully extended

and secure. Oil as necessary.
Clean optical parts carefully. Wipe brackets

before attaching sights. Check aUgn-

ment.

Lubricate following oil can points as re-
quired: Handbrake levers, pedestal car-
riage bolts, clevises, hinges, bogie engag-
ing eyebolts, platform support assemblies,
seat hinges and pins, leveling jack ratchet
wrenches, lock assembly, lunette shaft
and pin, hand wheel handles, outrigger
latches, trail lock linkage, gun jack, bogie
buffer latch,, etc.

Clean external parts. Wash with water or
solvent, dry cleaning as necessary » ■

Lubricating as required.

Recoil valve control cam and
slide.

Breech operating intermedi-
ate gear stud.
Operating handle latch

plunger.
Rammer rack guide

Rammer buffer rod bearing..
Rammer cylinders

Rammer arm bearings

Direct fire sights (M24 and
M26).

Tires __.

36 Handbrake ^

37 Electric brake

38 Lights (dials, fuze, breech,

tail),

39 Tools and accessories

40 Control bar hinge

> 27

O 28

31
32

33
34

Check to see that there is no binding and
observe gun during firing to see that the
recoil is proper upon elevation. Notify
Ordnance if necessary for adjustment.

To reach oiler, pull lever to rear. Oil with
correct seasonal lubricant.

Lubricate as required.

Lubricate as required. Fittings above and

below.
Lubricate as required.

Lubricate as required. {Caution: grease

sparingly).
Lubricate as required.

Oil cup, clamps, and pivots as necessary.
Avoid an excess of oil.

Maintain 70#/sq. in. air pressure, keep free
of grease and oils.

Adjust if necessary. (Normally no adjust-
ment is necessary) .

Check wiring for loose or broken connections
or wires, clean sockets and plugs. Cheek
brake current with ammeter. Clean drum
and magnetic facings if necessary. Check
shoes and magnet operation.

Clean and replace if necessary.

Check for completeness and availability,

that parts are clean and serviceable.
Lubricate as required.

Item

41 Recoil valve control cam and

slide o

42 Firing lever shaf t bearing

43 Breecli operating plunger

bearing and cam shaft.

44 Elevating gear case shaft

bearings and indicator drive
mechanism.

45 Elevating shaft lower bearing.

46 Elevating gear shaft bearing. .

47 Elevating remote drive gear
^ case and elevating worm

gear case.

48 Traversing gear case shaft

bearings and indicator
drive mechanism.

49 Traversing vertical shaft lower

bearing.

50 Cradle trunnion bearing

5 1 Top carriage bushing —

52 Rammer trip shaft bearing. __

53 Rammer trip latch\„ . _ -

54 Leveling rack bearing— left
§ Jack.

^ 55 Leveling mechanism^ sup-
^ port bearing.

Mainte=
nance

crew

Inter-
val

0 .

Maintenance required

Lubricate with greaie, OD,

Lubncate ag reguired.

Inner bearings reached from under breech.

Lubricate as required,

Do,
Do.

Do,

Do.
Doo
Do,

Do.
Do.

Do.

^^^Leveling mechanism, right
and left.

57 Leveling mechanism clamp

bearing.

58 Leveling jack handle bearing.

59 Ratchet drive rear bushing,

right and left.

60 Leveling socket bearing

61 Bogie guide roller

62 Buffer trunnion bearing. _

63 Buffer roller

64 Bogie buffer cylinder

65 Counterpoise gear box and

cylinder walls.

66 Counterpoise connecting rod

bearing.

67 Bogie frame support bearing.

68 Outrigger

69 Outrigger hinge pins

70 Trail hinge shaft

71 Trail lock lever bearing

72 Trail latch slide

73 Trail lock link pin

74 Traveling lock

75 Traversing rack, thrust and

clip bearings.

76 Wheel bearing

Do.

Do.
Do.

Do.
Do.
Do.
Do.

Lubricate sparingly.

Lubricate as required and after moving*
Lubricate as required.
Do.

Raise to traveling position; inspect joints

and surfaces for rust.
Lubricate as required.

Do.

Lubricate once every 6 months; clean and
grease oftener if wheels have been under
water.

■ 55. Remote Control System M2.

Item

77 Hydraulic speed gear.

78 Lag meter

79 Metal surfaces

80 Plugs and receptacles,

81 Whole system

82. Tubes and connections.
83 Elevation limit stops. __

84 Electrical.

85 Amplifier shock mountings.
^ 86 Oil filter

o 87 Hydraulic speed gear

Inter-
val

Maintenance required

D
D

W
W

. M
6M
6M

Keep oil level at line on window of A-end

housing.
Zero lag meter with power off.

Cautions Do not force.
Clean with dry cloth. Unpainted surfaces

should be cleaned with an oily cloth.
Keep clean and covered.
Put into operation at least once every day.

Check orientation, synchronization and

operation.

Check for leaks; notify maintenance if leaks
are found.

Test to see if gun approaches stop at its
full limit and moves off smoothly when
signal is reversed.

Check all external electrical connections for
grounds, broken connections, spidered
joints; see that soldered joints are covered
with glyptal lacquer.

Check and replace if worn.

Clean filter.

Drain and refill.

o
o

■ 56. Daily Maintenance Check List.

Battery Battalion.

Gun Serial No

Section III
CHECK LISTS

-MoNTH_

No.

1
2

Item of maintenance

Day

Gun and assembly

Gun mount

3
4
5
6
7
8
9

Gun tube*

Exposed recoil slides*

Recoil mechanism*

Recoil piston rod retainer*

Recoil valve control bar follower screw

Counterrecoil valve

Recoil throttling valve guides

•To be inspected before each firing if possible.

>
H
O

No.

Item of maintenance

Day

"14

Counterrecoil buffer

Breechblock

Breech recess

Breech operating shaft gears

Breech closing spring chain*

Firing mechanism

Spline shaft*

17
18

Breechblock crank, chain terminal crank and operating
crank.

Equilibrator

Elevating rack and pinion

Fuze setter

Power rammer

iJ..,U. - ' "

Auxiliary leveling screw

Direct fire sights

24
77

Miscellaneous

Hydraulic speed gear

78
79

Lag meter

Metal surfaces

Plugs and receptacles

Whole system

*To be inspected before each firing if possible, g
Persons performing maintenance operation will enter cbeok (|/) in proper column. For remarks use reverse §ide. p

■ 57, Weekly Maintenance Check List.

Battery Battalion Month .

Gun Serial No,

• CD

Item of maintenance

Week

No.

Gun and assembly

Recoil slides

xvecoli vaivc 0011 trui Licliu aiiu. feiiut; «

Breech operating intermediate gear stud

Operating handle latch plunger

Rammer rack guide

Rammer buffer rod bearing

Rammer cylinders

Rammer arm bearings

Direct fire sights (M24 and M26)

Tires

o
o

Handbrake

37~

Electric brake

38"

Lights (dials, fuze, breech, tail)

39"

Tools and accessories

Tubes and connections

83^

Elevation limit stops

Persons performing maintenance operation will enter check (V) in proper column. For remarks use reverse side.
58. Monthly Maintenance Check List.

_ Year ]

M Battery _ Battalion

Gun Serial No.

No.

40
41
42
43^

44"

Item of maintenance

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Control bar hinge

Recoil valve control cam and slide

Firing lever shaft bearing

Breach operating plunger bearing
and cam shaft

Elevating gear case shaft bearings
and indicator drive mechanism

d
o

o
d

No.

45
46
47

Item of maintenance

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Elevating shaft lower bearing

Elevating gear shaft bearing

Elevating remote drive gear case
and elevating worm gear case

Traversing gear case shaft bearings
and indicator drive mechanism

Traversing vertical shaft lower
bearing

Cradle trunnion bearing

51
52

Top carriage bushing

Rammer trip shaft bearing

Rammer trip latch

Leveling rack bearing, left jack

55
56

Leveling mechanism support bearing

Leveling mechanism, right and left

—Leveling mechanism clamp bearing

58--

leveling jack handle bearing

59~

Racket drive rear bushing, right
and left

Leveling socket bearing

Bogie guide roller

62
63

Buffer trunnion bearing

Buffer roller

Bogie buffer cylinder

Counterpoise gear box and cvlinder
walls

Counterpoise connecting rod bearing

Bogie frame support bearing

Outrigger

69~

Outrigger hinge pins

to"

Trail hinge shaft

Trail lock lever bearing

72~

Trail latch slide

73"

Trail lock Hnk pin

No.
74

75"

76
84
85
86
87

Item of maintenance

Traveling lock

Traversing rack, thrust and clip
bearings

Wheel bearing (6 mos)

Electrical

Amplifier shock mountings

Oil filter (6 mos)

Hydraulic speed gear (6 mos)

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Persons performing maintenance and operation will enter check (^/) in proper column. For remarks use reverse side.
[A. O. 300.7 (16 Aug 44).]

By. ORDER OF THE Secretary OF War: ^ ^ MARSHALL,

Official: ° ' Chief of ha ff.

J. A. ULIO,

Major General,

The Adjutant General. .

""^'TsTes'cribed in paragraph 9a, FM 21-6 exc p, D 44 (5) Sch (500) ; T of Opns^ (5^ HD
(5); Base Sectors (5); Sectors (5) ; Sub-Sectors (5 | Is W (5), Def U (5^,.

B 44 (5); R 44 (5); Bn 44 (5); IC 44: (15); AAATC (100); AAARTC (100). / - . , ,
IC 44: T/O & E 44-17; 44-117,
• For explanation of symbols, see FM 21-

RESTRICTED

FM 4-126

ANTIAIRCRAFT ARTILLERY
FIELD MANUAL

SERVICE OF THE PIECE
90-MM ANTIAIRCRAFT GUN
, ON MlAl MOUNT

Dissemination of restricted matter.^ — The information contained in re-
stricted documents and the essential characteristics of restricted material
m'ay be gven to any person known to be in the service of the United States
and to persons of undoubted loyalty and discretion who ^re cooperating in
Government work, but will not be communicated to the public or to the press
except by authorized military public relations agencies. (See also par. 186.
AR 380-5, 28 Sep 1942.)

UNITED STATES
GOVERNMEI^^ PRINTING OFFICE
WASHINGTON : 1943

WAR DEPARTMENT,
Washington 25, D. C, 25 October 1943.

PM 4-126, Antiaircraft Artillery Field Manual, Service of
the Piece, 90-MM Antiaircraft Gun on MlAl Mount, is
published for the information and guidance of all concerned.

[A. G. 300.7 (22 Sep 43).]

By order of the Secretary of War :

G. C. MARSHALL,

Chief of Staff.

Official :

J. A. ULIO,

Major General,

The Adjutant General.

Distribution :

BandH 44 (5); IC44 (15).

(For explanation of symbols see PM 21-6.)

TABLE OP CONTENTS

Paragraphs Page

Chapter 1. General 1-2 1

Chapter 2. Organization of gun section 3-4: 2

Chapter 3. Drill procedures.

Section I. General 5-6 4

II. Preliminary commands and forma-
tions 7-12 5

III. Emplacement and march order 13-16 9

IV. Preparation for fire 17-21 28

V. Antiaircraft artillery drill 22-25 37

VI. Direct fire drill 26 -29 41

Chapter 4. Notes on materiel.

Section I. Emplacement 30-31 45

II. Direct fire sights 32-39 54

Chapter 5. Safety precautions _ 40-43 60

Chapter 6. Destruction of materiel 44-51 62

Appendix. List of references 68

Index 69

FM 4-126

ANTIAIRCRAFT ARTILLERY FIELD MANUAL

SERVICE OE THE PIECE
90-MM ANTIAIRCKAFT GUN ON MlAl MOUNT

(This manual supersedes FM 4-126, 2 October 1942, including C 1,
28 October 1942, C 2, 28 November 1942, C 3, 23 January 1943, C 4,
19 March 1943; section II, Training Circular No. 48, and section I,
Training Circular No. 81, War Department, 1942.)

CHAPTER 1

GENERAL

H 1. Scope. — This manual prescribes a systematic" procedure
to be followed by the ^un crew for service of the piece for the
90-mm antiaircraft gun Ml on mount MlAl. Included are
drill procedures for emplacement and march order, prepara-
tion for fire and artillery drill. Description of materiel, care
and preservation, malfunctioning and correction, and ammu-
nition are covered in TM 9-370 and TM 9-2642. Referenced
are listed in the. appendix; they are suggested for further
study of materiel covered in the rnanual and allied topics.

B 2. Decontamination. — For information on decontamina-
tion of materiel, see TM 9-850, FM 21-40, and 3-series TM's.

CHAPTER 2 ^
ORGANIZATION OF GUN SECTION

■ 3. GiTN Section. — a. The gun section consists of the gun
commander, a gun squad of nine men, including the gunner,
and an ammunition squad of six men, including the ammu-
nition chief. The gun commander commands the gun sec-
tion and also the gun squad. The ammunition chief is in
charge of the ammunition squad.

b. The members of the gun section are designated as
follows:

GC Gun commander.
G Gunner.

1 Fuze setter loader.

2 Elevation setter.

3 Fuze setter operator.

4 Loader.

5 F\ize range setter.

6 Ammunition relayer.

7 Azimuth setter.

8 Ammunition relayer.
AC Ammunition chief.

9 Ammunition handler.

10 Ammunition handler.

11 Ammunition handler.
. 12 Ammunition handler.

13 Chauffeur.

■ 4. Duties of Personnel. — a. The gun commander is in
charge of the entire gun section and is responsible to the
battery executive for the —

(1) Training and efficiency of the personnel in his section.

(2) Condition, care, and preparation for action of all
materiel and ammunition under his charge.

(3) Observance of all safety precautions pertaining to the
service of the piece.

(4) Police of gun position.

(5) Enforcement of camouflage and gas discipline.

(6) Record of number of rounds fired.

(7) Care and return of empty cartridge cases to the proper
agency.

90 -MM ANTIAIRCRAFT GUN ON MlAl MOUNT 4

(^) Preparation of field fortifications for protection of
the gun, personnel, and ammunition.

(9) Training of all members of gun section in taking
alternate positions in the gun section.

(10) Performance of those duties set forth in the drill
procedures.

b. The gunner is responsible for the —

(1) Observance of all safety precautions pertaining to
the firing of the gun.

(2) Condition, care, and preparation for firing of the
breech and firing mechanism.

(3) Performance of those duties set forth in the drill
procedures.

c. The ammunition chief is in charge of the ammunition
squad and is responsible to the gun commander for the—

(1) Training and efficiency of the personnel under his
charge.

(2) Observance of all safety precautions in the storage,
care, and service of ammunition.

(3) Proper care and preparation of ammunition for the
gun.

(4) Correct recording of required ammunition data.

(5) Uninterrupted service of ammunition to the gun posi-
tion during the course of action.

(6) Cleaning and disposition of empty cartridge cases.

(7) Enforcement of camouflage and camouflage disci-
pline, and gas discipline at ammunition shelters.

(8) Performance of those duties set forth in the drill
procedures.

d. The members of the gun squad are responsible for the
duties as set forth in the drill procedures and such other
duties as may be designated by the gun commander.

e. The members of the ammunition squad, with exception
of No. 13, are responsible for the duties as set forth in the
drill procedures and such other duties as 'may be designated
by the ammunition chief or gun commander.

/. No. 13, the prime mover driver, is responsible for the
care and maintenance of the prime mover, and will remain
with the prime mover, unless other duties are designated by
the ammunition chief or gun commander.

CHAPTER 3

DRILL PROCEDURES

Section I. General

II. Preliminary commands and formations.

III. Emplacement and march order

IV. Preparation for fire

V. Antiaircraft artillery drill-

VI. Direct fire drill

Paragraphs
5-6

7-12
13-16
17-21
22-25
26-29

Section I

GENERAL

■ 5. Explanation. — The drills are presented in chronologi-
cal sequence of action, with explanatory notes. Each action
begins with the numbers or abbreviations signifying the
members of the gun section concerned in that action; these
numbers or abbreviations are at the left margin. Each main
operation performed is separated from other main operations

by 0 In emplacement of the gun and march order,

the front of the mount is the towing or trail end. Left and
right sides of the mount are determined by standing at the
rear and facing the front.

■ 6. Instructions. — The drill prescribed herein will be
adhered to strictly, both to prevent injury to materiel and to
produce maximum operating efficiency of the gun section.
Drill is conducted in silence except for commands and reports.
The gun section must be drilled until all reactions to com-
mands are automatic, instant, and effective. Errors are cor-
rected instantly and on the spot. Drill is conducted at the
fastest pace at which the gun section can operate smoothly.
The ultimate in precision and speed is the goal. Battery
officers must supervise and coach the gun commander to
make sure that the foregoing instructions are carried out and
that the maximum efficiency of the gun section is reached.

90 -MM ANTIAIRCRAFT GUN ON MlAl MOITNT 7

^ Section II

PRELIMINARY COMMANDS AND FORMATIONS
■ 7. FALL IN.

The gun section assembles in two ranks, with the gun squad
on the right, facing GC. The interval is 4 inches between
files and 40 inches between ranks. GC takes his post three
paces in front of the center of the line on which the front
rank is to form. The primary purpose of the command
FALL IN (and subsequent commands count off and call off)
is to verify the gun section.

Figure 1. — ^Positions of personnel at command fall in.

GC commands: FALL IN.
G takes his post as guide on the right, facing GC.
2, 4, 6, 8, AC, 10, 12 form the front rank,
1, 3, 5, 7, 9, 11, 13 form the rear rank — (1, 3, 5, 7 cover off
2, 4, 6, 8; and 9, 11 cover off 10, 12).

Note. — GC forms the gun section in this formation
when required and locates the assembly point so as to suit
the particular situation best.

8-10 ANTIAIRCRAFT ARTILLERY FIELD MANUAL

■ 8. COUNT OFF.

The gun section being in formation,
GC commands: COUNT OFF.
G reports "Gunner."

1 to 8 report their numbers consecutively.
AC reports "Ammunition chief."
9 to 13 report their numbers consecutively.

B 9. CALL OFF.

The gun section being in formation,
GC commands: CALL OFF.
G reports "Gunner."

1 reports "Fuze setter loader."

2 reports "Elevation setter."

3 reports "Fuze setter operator."

4 reports "Loader."

5 reports "Fuze range setter."

6 reports "Ammunition relayer."

7 reports "Azimuth setter."

8 reports "Ammunition relayer."
AC reports "Ammunition chief."

9 reports "Ammunition handler."

10 reports "Ammunition handler."

11 reports "Ammunition handler."

12 reports "Ammunition handler."

13 reports "Chauffeur."

■ 10. CHANGE ORDER:

The gun section being in formation,
GC commands: CHANGE ORDER.
G falls out to rear and takes position of 13.

1 takes position of G.
AC takes position of 8.

9 takes position of AC.

2 through 8 take position of next lower number.
10 through 13 take position of next lower number.

All members move simultaneously to new positions.

90-MM ANTIAIRCRAFT GUN ON MlAl MOUNT

■ 11. DETAILS, POSTS.
GC commands: DETAILS, POSTS.
1, 2, 3, 6, 7, 8 remove and fold gun cover and place it in

a convenient place.
G places a wiper of cotton waste and a can of oil in a

convenient place.
4 procures chamber and bore sponge and wiper of cotton
waste.

3 removes muzzle cover and deposits it at designated place.
G, 4 remove breech cover and deposit it at designated place.

FiGXTRE 2. — ^Positions of personnel of gun squad at command details,

POSTS.

564277**— 43 2 7

11-12

ANTIAIRCRAFT ARTILLERY FIELD MANUAL

G takes post at right rear of gun, opposite to and facing
breech.

1 takes position immediately in the rear of the fuze setter,
facing it, standing on gunner's platform.

2 takes post at elevation station, seated on elevation setter's
seat, facing elevation indicator regulator.

3 takes post at right rear of fuze range setter, facing fuze
setter.

4 takes post about 2 feet to left and rear of breech facing
gunner.

5 takes post at fuze range setter's station, seated on fuze
setter's seat facing fuze setter.

6 takes post directly in rear of fuze setter, standing on
ground and facing 1.

7 takes post at azimuth station seated on azimuth setter's
seat facing azimuth indicator regulator.

8 takes post on ground about 3 or .4 feet from gunner's plat-
form and facing 6.

9 takes post at ammunition stack ready to remove protec-
tive covers.

A.C posts 10, 11, 12 to insure a continuous supply of ammu-
nition to gun position.
10, 11, 12 take positions to insure continuous supply of am-
munition to gun position.
13 takes post at prime mover, unless ordered otherwise by
AC or GC.

a 12. REST.

GC commands: REST, carries out instructions as to air
guards, manning details, reliefs, gas discipline, camou-
flage, and local security. He makes sure that full ad-
vantage is taken of the opportunity by the gun section
to improve position, prepare and replenish ammunition,
perform maintenance, and make tests and' adjustments.
The gun section should be given a chance to relax and
rest, but the command REST does not mean loaf.

90 -MM ANTIAIRCRAFT GUN ON MlAl MOUNT

Section III

EMPLACEMENT AND MARCH ORDER

B 13. ElVlPIiACEMENT OF GUN WITHOUT PRIME MOVER.

Note. — Since a prime mover will be used whenever avail-
able, it is assumed in this section that the gun has already
been uncoupled from the prime mover, and that the rear
outrigger is extended and broken at the outer joint.

GC commands: PREPARE FOR ACTION.

AC during emplacement of the gun directs 9, 10, 11, 12, 13
in the unloading and placing of ammunition, gun tools,
cables, camouflage equipment, and other material needed
at gun position. 9, 10, 11, 12 prepare ammunition for
service.

Figure 3.

G, 1, 2, 3, 4, 7, 8 take off gun cover— lay it at a convenient

place, temporarily unfolded.
5, 6 remove canvas covers from counterpoise cylinders.

ANTIAIRCRAFT ARTILLERY FIELD MANUAL

1, 2 check that hand brakes are set.

5, removes equillbrator piston stop from equilibrator and
Inserts It In holder on top of equilibrator cylinder.

Figure 4.

1, 3, 5, 7 extend and pin left outrigger.

2, 4, 6, 8 extend and pin right outrigger.

FiGTJBE 6.

90-MM ANTIAIRCRAFT GUN ON MlAl MOUNT 13

1, 3, 5, 7 remove left platform and lay it aside.

2, 4, 6, 8 remove right platform and lay it aside.
G unfastens transom cap; removes muzzle cover.

Figure 6.

2 elevates the gun slightly to clear traveling lock.

0-, 1 unpin traveling lock brace and lower the traveling lock,

pinning it to the trail.
5, 6, 7, 8 extend and pin the rear outrigger.

G retracts bogie buffer plunger, using socket wrench.
1, 3, 4 at the trail gently tip the gun back on the rear
outrigger.

5, 6j 7, 8 at the rear outrigger, assist in tipping the gun
back on the rear outrigger.

Caution. — ^The rear outrigger must be extended and
pinned before the gun is tipped back.

G pulls out latch on side of buffer cylinder and swings
the forward end of the buffer cylinder down. (The latch
reengages when the cylinder has moved to the lower
position.)
1, 2 release hand brakes.

13 ANTIAIRCRAFT ARTILLERY FIELD MANUAL

FIGUBE 7.

G, 3, 4 at the trail partially crush mount by exerting down-
ward pressure on trail, forcing it to ground.

5, 6, 7, 8 at rear outrigger assist in crushing mount by pulling
up on rear outrigger.

7, 8 pull out on the crank handles of the gear boxes, and
swing the gear boxes to the front over the ends of the cyl-
inders, fastening them in place with the swing bolts and
wing nuts.

Note.— /F COUNTERPOISE CYLINDER RODS ARE
NOT RETRACTED FAR ENOUGH TO PERMIT PUTTING
THE GEAR BOXES IN PLACE, THE MOUNT MUST BE
CRUSHED FURTHER BY SEVERAL MEN JUMPING ON
EACH SIDE OUTRIGGER.

1, 2 loosen locking nuts only on the bogie engaging eye hooks
and place the socket wrenches on the bogie securing bolts
preparatory to loosening them.

2 elevates gun to maximum.

3, 4, 7, 8 crank bogie down until the pedestal rests firmly on
the ground, and the wheels can be turned.

90 -MM ANTIAIRCRArX GUN ON MlAl MOUNT

Figure 8.

5, 6 place fuze setter bracket and seat in firing position and
place the fuze setter in its bracket; connect cable to fuze
setter junction box.

Figure 9.

ANTIAIRCRAFT ARTILLERY FIELD MANUAL

1, 2 loosen and disengage bogie securing bolts.

1, 2, 3, 4, 5, 6, 7, 8 take positions at and support the trail.

G pulls out electric brake cable plug and places it in dummy

socket; disengages trail lock rocker arm swing bolt, and

then allows trail lock rocker arm to swing to maximum

height as trail is lowered.
1, 2, 3, 4, 5, 6, 7, 8 lower trail to its lower position after trail

lock rocker arm is loosened.
G moves trail lock rocker arm down and ref astens it by means

of swing bolt after trail is lowered.

Note.— It may be necessary to dig out under entire
length of trail to permit it to be locked in lower position.

1, 2 loosen both nuts on each bogie engaging eye hook.
3, 4 push in on bogie engaging operating handles; put bogie
hub wrenches on the wheels.

Note. — It may be necessary for 7 and 8 to crank bogie up
slightly until wheels contact ground before bogie engaging
eye operating handles can be pushed in. Never force the
operating handles.

PIGXJBB 10.

90-MM ANTIAIRCRAFT GUN ON MlAl MOUNT 13

G, 6, 6, 7, 8 roll out bogie.

3, 4 assist rolling bogie by turning wheels with bogie hub
wrenches.

1, 2 ride the bogie, holding up on bogie engaging eye hooks
until they clear the pedestal, then dropping them; ma-
nipulate hand brakes as directed by GC.
GC checks clearance between top of bogie frame and bottom
of equilibrator cylinder before bogie is rolled out.

FIGXJRE XX,

G loosens auxiliary leveling screw at front of mount, using
^a-inch rod, and keeps it free from binding as mount is
leveled,

7, 8 level mount by means of the leveling jacks (a leveling
vial is mounted on each jack) . Call "Level** when gun is
level.

G tightens auxiliary leveling screw by screwing it down as
soon as the mount has been leveled.
GC verifies leveling of mount.

7, 8 tighten jack clamps and place jack ratchets in neutral
position. (No. 7 places his jack handle as close to the
rear outrigger as possible to prevent breakage of the
handle by the platform reinforcing angle.)

554277*'— 43 3 15

13-14 ANTIAIRCRAFT ARTILLERY FIELD MANUAL

5, 6 replace canvas covers on counterpoise cylinders.

2, 7 lower their seats to the firing position.

1, 3 lay cable from gun to main junction box — connect cable

at main junction box.
7 connects cable to cable receptacle on left side of pedestal.

Figure 12.

1, 3, 5, 7 put left platform in place on outriggers and
fasten it.

2, 4, 6, 8 put right platform in place and fasten it.

G, 1, 2, 3, 4, 5, 6, 7, 8, fold canvas cover and place it on
bogie buffer cylinder and place dirt under those parts of
the outriggers which do not touch the ground.

■ 14. EMPLACEMENT OP GtJN USING PRIME MOVER.

GC commands: PREPARE FOR ACTION.
G, 2, 4, 6, 8 dismount from prime mover from the right
side.

1, 5, 7 dismount from prime mover on left side.

3 walks out on gun tube.

8 tosses out lifting bar.

4, 7 bring out wheel wrenches.

1, 2 bring out bogie socket wrenches.

90-MM ANTIAIRCRAFT GUN ON MlAl MOUNT 14

5, 6 bring out bogie ratchet wrenches.
AC during emplacement of gun directs 9, 10, 11, 12 in the
unloading of ammunition, gun tools, cables, camouflage
equipment, and other material needed at the gun posi-
tion. 9, 10, 11, 12 prepare ammunition for service.

G, 1, 2, 3, 4, 5, 6, 7, 8 untie gun cover, take it off to the

rear, and lay it on the ground.
1, 2 loosen the wing bolts holding the platform to the trail.v
3 unfastens outrigger safety chain.

5, 6 remove canvas, covers from counterpoise cylinders.
G takes position at the bogie buffer.

5, 6, 7, 8 unlatch, extend, and pin the rear outrigger in its
extended position. ,

GC orders all men, except G at the bogie buffer, to stand
clear of the gun; directs 13 to set the electric brakes and
then to drive the prime mover forward,, compressing the
spring in the bogie buffer with the axle lug.
G screws down on bogie buffer plunger retracting hand-
wheel as the bogie buffer spring is compressed.

GG when buffer spring has been sufficiently compressed,
orders prime mover backed up until G can pull out
on the latch on the side of the buffer cylinder and swing
the forward end of the buffer cylinder down.
G pulls out on latch on side , of buffer cylinder and
swings forward end of the buffer cylinder down. (The
latch reengages when the buffer cylinder has moved to
lower position. )

GC orders prime mover to be driven forward- again, partially
crushing the gun mount, until the counterpoise cylinder
rods have entered into the counterpoise cylinders far
enough to allow 7 and 8 to pull out on the crank handles
of the gear boxes, swing them over the front 'ends of the
cylinders, and fasten them in place with the swing bolts
and wing nuts.

7, 8 pull out on crank handles of gear boxes, swing the
boxes to the front over the ends of the cylinders, and
fasten tihem in place with the swing bolts and wing nuts.

ANTIAIRCRAFT ARTILLERY FIELD MANUAL

GC directs the prime mover, driver to release the bogie
electric brakes.

1 unfastens the break-away chain and pulls the electric
cables out of the truck and bogie, and inserts them in the
dummy receptacle on the left side of the trail.

2 inserts lifting bar in the end of the trail.

G takes position immediately behind the lifting bar.
1, 2 take position at lifting bar.

G disconnects the trail from prime mover. (Gunner must
not stand between prime mover and lifting bar.)
GC directs prime mover to move out.
1, 2 press down on trail.

3, 4, 5, 6, 7, 8 lift rear outrigger, lowering the trail to
the ground.

8 extend and pin the right outrigger.

7 extend and pin the left outrigger-

6, 8 remove the right platform and lay it aside.

7 remove the left platform a-nd lay it aside.

G unfastens transom cap.

5 removes the equilibrator piston stop from the equilibrator
and puts it in its holder on top of equilibrator.

2 takes position at elevating handwheel and elevates the

gun slightly to clear the traveling lock.
G^ 1 unpin traveling lock brace, lower, traveling lock, and
pin it to the trail.

2 elevates gun to maximum.

G, 1, 3, 4, 5, 6 at the trail, tip the gun gently back on the
rear outrigger.

7, 8 at rear outrigger assist in tipping gun back on rear
outrigger.

1, 2 loosen lock nuts only on bogie engaging eye hooks;
place socket wrenches on bogie securing bolts prepara-
tory to loosening them.

90 -MM ANTIAIRCRAFT GUN ON MlAl MOUNT

7, 8 crank bogie down- until the pedestal rests firmly on

the ground and the wheels can be turned.
3, 4 assist 7, 8 crank bogie down.

5, 6 place fuze setter bracket and seat in firing position
and place fuze setter in its bracket; connect cable to fuze
setter junction box.

1, 2 loosen and disengage bogie securing bolts.

1, 2, 3, 4, 5, 6, 7, 8 support weight of trail.

G disengages trail lock rocker arm swing bolt preparatory
to lowering the trail; as trail is lowered allows trail lock
rocker arm to swing up to its maximum angle.

1, 2, 3, 4, 5, 6, 7, 8 move trail down to its lower position.

G moves trail lock rocker arm down and refastens it by
means of the swing bolt.

Note. — It. may be necessary to dig out under entire
length of trail to permit it to be locked in lower position.

1, 2 loosen both nuts on each bogie engaging eyebolt.
3, 4 push in on bogie engaging eye operating handles; put
hub wrenches on the wheels.

Note. — It may be necessary for 7 and 8 to crank bogie
up slightly until wheels contact ground before operating
handles can be pushed in. Never force the operating
handles.

G, 3, 4, 5, 6, 7, 8 roll the bogie out, 3 and 4 using bogie

hub wrenches on wheels.
1, 2 ride the bogie, holding up on the bogie engaging eye

hooks until they clear the pedestal, then dropping them

and manipulating the brakes as directed by GC.
GC checks clearance between top of bogie frame and bottom

of equilibrator cylinder before bogie is rolled out.

G loosens auxiliary leveling screw at the front of the mount,

using the l^-inch rod, and keeps it from binding as the

mount is leveled.
7, 8 level gun by means of the leveling jacks (a leveling

vial is mounted on each jack). Call "Level'* when gun

is level.

14-15 ANTIAIRCRAFT ARTILLERY FIELD MANUAL

G tightens auxiliary leveling screw by screwing it down as
soon as the gun has been leveled.
GC verifies level of gun.

7, 8 tighten jack clamps and place jack ratchets in the
neutral position (No. 7 places his jack handle as close to
the rear outrigger as possible to prevent breakage of the
handle by the platform reinforcing angle) .

5, 6 replace canvas covers on counterpoise cylinders.

2, 7 lower their seats to the firing position.

1, 3 lay cable from gun to main junction box; connect cable
at main junction box.

7 connects cable to cable receptacle on left side of pedestal.

1, 3, 5, 7 put left platform in place on outriggers and
fasten it.

2, 4, 6, 8 put right platform in place on outriggers and
fasten it.

G, 1, 2, S, 4, 5, 6, 7, 8 fold canvas cover and place it on
the bogie buffer cylinder; place dirt under those parts
of outriggers which do not touch the ground.

B 15. MARCH ORDER WITHOUT PRIME MOVER '

GC commands: MARCH ORDER.

1, 3, 5, 7 remove, fold, and lay aside left platform.

2, 4, 6, 8 remove, fold, and lay aside right platform.

G loosens the auxiliary leveling screw and keeps it loose

while the leveling jacks are centered.
7, 8 center leveling jacks and call "Center."

Note. — The center of jack travel is indicated by marks
on the jack body.

G tightens auxiliary leveling screw by screwing it down,
after jacks are centered. ^
7, 8 tighten jack clamping screws.
5^ 6 remove canvas counterpoise covers.
3, 4 put on bogie hub wrenches preparatory to rolling
bogie in.

90-MM ANTIAIRCRAFT GUN ON MlAl MOUNT 15

2 elevates gun to maximum — folds his seat and footrest
in the traveling position.

7 sets the gun to zero traverse (the position where the trav-
erse pointer at the lower rear edge of the top carriage
is directly in line with a groove in the top of the left jack
slide cover) ; folds and pins the azimuth setter's seat and
footrest in the traveling position; disconnects the cable
from the cable receptacle on the left side of the pedestal
and replaces cap on plug and receptacle.

5 disconnects cable from fuze setter junction box; unpins
fuze setter bracket.

5, 6 remove fuze setter from its firing position and put it
in traveling bracket.

G, 5, 6 roll bogie in, taking particular care not to bump

any part of the mount.
1, 2 ride the bogie and hold the bogie engaging eye hooks

clear of the pedestal.
3, 4 assist in rolling bogie in by manipulating the hub

wrenches.

GC checks clearance between bottom of equllibrator cylinder
and top of the bogie frame as the bogie is rolled in.

Note. — Since the mount settles during firing, it may be
necessary for 7 and 8 to crank bogie down or to dig a
trench for the wheels to provide clearance when the bogie
is rolled in. '

7, 8 crank bogie down until the bogie engaging eye oper-
ating handles can be pulled all the way out.

3, 4 pull out on bogie engaging eye operating handles until
they are locked in place by the pawls.

1, 2 tighten by hand the lower nuts in the bogie engaging
eye hooks, leaving sufficient clearance to permit engaging
the bogie securing bolts when the trail is raised.

G loosenis the wing nut and drops the swing bolt, disen-
gaging the trail lock rocker arm; commands when to lift
the trail and then pulls up on rocker arm as trail is
raised, and lower§ rQCker arm again,

ANTIAIRCRAFT ARTILLERY FIELD MANUAL

1, 2, 3, 4 5j 6, 7, 8, at gunner's command,, lift forward
end of trail and hold it until trail is locked in the upper
position.

G fastens the trail lock rocker arm again by means of swing
bolt and wing nuts; plugs electric brake cable into socket
of bogie,

1, 2, with the trail in the "up" position, engage the bogie
securing bolts and tighten and lock the nuts on the
bogie engaging eye hooks and on the bogie securing bolts;
set hand brakes.

3, 4, 7, 8 crank bogie up until the gear boxes can be dis-
engaged and locked in traveling position (by pushing in
on crank handles).

G takes position at bogie buffer cylinder.

1, 2 release hand brakes at GC's command.

3^ 4, 5, 6, 7, 8, as the brakes are released, give a strong
upward push to the trail. (This causes the lug on the
bogie axle to swing up against the rubber bumper on
top of the bogie directly to the rear of the bogie buffer.)
GC commands: RELEASE BRAKES.

G pulls out on the latch shaft handle and swings the front
end of the buffer cylinder up until the bogie buffer roller
is directly in front of the axle lug; engages latch on side of
buffer cylindero

5, 6, 7, 8 at rear outrigger tip the mount gently forward.
1, 3, 4 at the trail assist in tipping mount forward.
2 depresses gun to 300 mils.

G loosens handwheel on bogie buffer, as the lug on tne
bogie axle comes forward against the bogie buffer plunger.
5, 6 break rear outrigger.

G, 1 raise traveling lock brace.
2, depresses gun into traveling lock.

G swings transom on top traveling lock over the gun tube,

fastens it, and replaces muzzle cover.
5 removes the equilibrator piston stop from the holder

on top of the equilibrator and inserts it in the equilibrator

. 90-MM ANTIAIRCRAFT GUN ON MlAl MOUNT 15

cylinder head; fastens it- with the equilibrator piston
stop pin.

G plugs electric brake cable into the socket of the bogie.

2, 4, 6, 8 put right platform on the trail and fasten it in
position.

1, 3, 5, 7 put left platform on the trail and fasten it in
position.

2, 4^ 6, 8 fold and latch the right outrigger in traveling
position.

1, 3, 5, 7 fold and latch the left outrigger in traveling
position.

G, 1, 2 take position at the trail.
5, 6 extend and pin rear outrigger.
3, 4, 5, 6, 7, 8 take positions at the rear outrigger.
GC directs prime mover to back up to couple mount.
G, 1, 2 couple mount to prime mover.

3, 4, 5, 6, 7, 8 at the rear outrigger maneuver mount as
directed by GC to assist in coupling gun to prime mover.

5, 6, 7, 8 fold and latch rear outrigger.

3 climbs on top of mount, secures outriggers with outrigger

chain, and remains there to help put canvas cover in

place.

1 fastens the break-away chain to the prime mover, plugs
brake cable into the prime mover; takes the lifting, bar
out of trail and puts it in the prime mover.

1, 2, 4, 5^ 6, 7, 8 put the gun cover on the gun and fasten
it in place.

3 carries the cover up over the tube from the rear by walk-
ing along the tube.

3, 8 disconnect cable at main junction box; reel up cable.
1, 2 place bogie socket wrenches in prime mover.

4, 7 place wheel wrenches in prime mover.

5, 6 place bogie ratchet wrenches in prime mover.

554277°— 43 4 23

15-16 ANTIAIRCRAFT ARTILLERY FIELD MANUAL

GC inspects gun for travel and checks electric brakes.

AC, 9, 10, 11, 12 while the gun is being prepared for travel,
check to see that all rounds are set at SAFE; restore
rounds to fiber containers and replace in wooden boxes;
load ammunition on proper truck; load gun tools, cables,
camouflage equipment, and other material in proper
vehicle.

Note. — Rounds that have been removed from their con-
tainers will he kept segregated when repacked and used
first in subsequent firings.

13 prepares prime mover for travel prior to bringing prime
mover to gun position.

1, 3, 5, 7 take places in prime mover on left side.

G, 2, 4, 6, 8 take places in prime mover on right side.
GC, 13 take places in cab of prime mover. (See fig. 13.)
AC, 9, 10, 11, 12 take places in proper truck.

0 © © ©

(13

(ac)

Figure 13. — Position of gun squad in truck prime mover. (For
positions in tractor prime mover, see FM 4-127.)

B 16. MARCH ORDER USING PRIME MOVER.

GC commands: MARCH ORDER.

1, 3, 5, 7 remove, fold, and lay aside left platform.

2, 4, 6, 8 remove, fold, and lay aside right platform.

90-MM ANTIAIRCRAFT GUN ON MlAl MOUNT 16

G loosens auxiliary leveling screw and keeps it loose while

the leveling jacks are being centered.
7, 8 center leveling jacks and call "Center."

Note. — The center of jack travel is indicated hy marks
on jack "body.

G tightens auxiliary leveling screw by screwing it down

after jacks are centered.
7, 8 tighten jack clamping screws-
5, 6 remove canvas counterpoise^ covers.
3, 4 put on bogie hub wrenches preparatory to rolling
bogie in.

2 elevates gun to maximum; folds his seat and footrest in
the traveling position.

5 disconnects cable from fuze setter junction box; unpins
fuze setter bracket.

5, 6 remove fuze setter from its firing position, and. put it
in traveling bracket.

7 sets gun to zero traverse (the position where the traverse
pointer at the lower rear edge of the top carriage is
directly in line with a groove in the top of the left jack
slide cover) ; folds and pins the azimuth setter's seat and
footrest in traveling position; disconnects the cable from
the cable receptacle on the left side of the pedestal and
replaces the caps on the plug and receptacle.

G, 5, 6 roll pogie in, taking particular care not to bump

any part of the ipount.
1, 2 ride the bogie and hold the bogie engaging eye hooks

clear of thp pedestal.
3, 4 manipulate the hub wrenches.

GC checks cle^,rance between bottom of equilibrator cylinder
and top of bogie frame as the bogie is rolled in.

l^OTK.-r— Since the mount settles during firing, it may he
necessary for 7 and 8 to crank bogie down or to dig a
trench for the wheels to prpvide clearance when the bogie
is rolled in.

ANTIAIRCRAFT ARTILLERY FIELD MANUAL

7, 8 crank bogie down until the bogie engaging eye operat-
ing handles can be pulled all the way out.

3, 4 pull out on bogie engaging eye operating handles until
they are locked in place by the pawls.

1, 2 tighten by hand the lower nuts in the bogie engaging
eye hooks, leaving sufficient clearance to permit engaging
the bogie securing bolts when the trail is raised; set hand
brakes.

G loosens the wing nut and drops the swing bolt, disengag-
ing the trail lock rocker arm; commands when to lift the
trail and then pulls up on rocker arm as trail is raised,
and lowers rocker arm again.

1, 2, 3, 4, 5, 6, 7, 8, at gunner's command, lift forward end
of trail and hold it until trail is locked in the upper
position.

G fastens the trail lock rocker arm again by means of swing
bolt and wing nuts; plugs electric brake cable into socket
of bogie.

1, 2 with the trail in the "up" position, engage the bogie
securing bolts and tighten and lock the nuts on the bogie
engaging eye hooks and on the bogie securing bolts.
G, 1 raise traveling lock brace.

2 depresses gun into traveling lock.

G swings transom cap over tube and locks it; puts on muzzle
cover.

5 removes equillbrator piston stop from holder on top of
equilibrator and inserts it in equillbrator cylinder head;
fastens it with equilibrator piston stop pin. ^

1, 3, 5, 7 put left platform on trail and fasten it in posi-
tion.

2, 4, 6, 8 put right platform on trail and fasten it in posi-
tion.

1, 3, 5, 7 fold and latch left outrigger in traveling position.

2, 4, 6, 8 fold and latch right outrigger in traveling posi-
tion.

90 -MM ANTIAIRCRAFT GUN ON MlAl MOUNT 16 .

G, 1, 2 take positions at the trail.
3, 4, 5, 6, 7, 8 take positions at the rear outrigger.
GC directs prime mover to back up to couple mount.
G, 1, 2 couple mount to prime mover.

3, 4, 5, 6, 7, 8 at rear outrigger maneuver mount as di-
rected by GC to assist in coupling gun to prime mover.

7, 8 crank bogie up until gear boxes can be disengaged and
locked in traveling position.

1, 2 release hand brakes.

& plugs electric brake cable into prime mover and connects
break-away chain. Plugs in electric plug on bogie.

5, 6 put canvas covers on counterpoise cylinders.

1, 2, 4, 7, 8 place rear outrigger in traveling position.

3 climbs on top of mount, secures outriggers with outrigger
chain, and remains there to help put canvas' cover in
place.

GC directs prime mover driver to turn on electric brakes;
directs prime mover driver to back up to raise bogie so
that bogie buffer cylinder can be put in place against
the axle lug; directs prime mover to stop when bogie
buffer cylinder is in place.
G pulls out on latch shaft handle and swings the bogie
buffer cylinder down in place against the axle lug on the
bogie axle; engages latch on side of buffer cylinder;
loosens bogie buffer handwheel as far as it will go.

1, 2, 4, 5, 6, 7, 8 put gun cover on gun and fasten it in
place.

3 carries cover up over tube from the rear by walking
along the tube.

3, 8 disconnect cable at main junction box; reel up cable.
1, 2 place bogie socket wrenches in prime mover.

4, 7 place wheel wrenches in prime mover.

5, 6 place bogie ratchet wrenches in prime mover.
GC checks gun for travel and checks electric brakes.

16-17 ANTIAIRCRAFT ARTlL^^ER^ FIELD MANUAL

AC, 9, 10, 11, 12, while the gun is being prepared for travel,
check to see that all rounds are set at SAFE; restore
rounds to fiber containers and replace in wooden boxes;
load ammunition on proper truck; load gun tools, cables,
camouflage equipment, and other material in proper
vehicle.

Note.— Rounds that have been removed from their
containers will be kept segregated when repacked and
used first in subsequent firings.

13 prepares prime mover for travel prior to bringing prime
mover to gun position.

1, 3, 5, 7 take places in prime mover on left side.

G, 2, 4, 6, 8 take places in prime mover on right side.
GC takes place in cab of prime mover. (See fig. 13.)
AC, 9, 10, 11, 12 take places in proper truck.

Section IV

PREPARATION FOR FIRE

■ 17. EXAMINE GUN.— The gun is examined each time
it is emplaced preparatory to firing, after each action,
and at least once a day in the theater of operations. A
schedule for examine gun must be worked out so that
only one gun in a battery will be out of action at any
one time.

GC commands: EXAMINE GUN; inspects gun, carriage, and
other materiel; checks to see that gun is properly
emplaced and level; checks to see that all moving parts
are properly lubricated; examines for leaks around recoil
mechanism; supervises 6, 8 in determining that reserve
oil and gas pressure in recoil and recuperator systems
are sufficient,

4 assists G in examining, cleaning, and oiling breech mech-
anism; sees that breech operating cam lever is set for
^'Automatic"; if necessary, assists G in sponging and
cleaning bore of gun.

90 -MM ANTIAIRCRAFT GUN ON MlAl MOUNT

G assisted by 4, examines, cleans, and oils breech mech-
anisms; removes, examines, cleans, and oils firing
mechanism and replaces it in breech block; checks ram-
mer to determine that it' is operating properly; checks
hand cocking lever and firing lever to determine that
they are operating properly; checks proper seating of
detent in spline shaft; examines bore and chamber of
gun and, if necessary, sponges and cleans bore assisted
by 1, 4, 6, and 8.

Note. — Check proper seating of detent in spline shaft
by observation or feel at night.

1. Detent is present.

2. Detent is flush with bushing — bushing is flush with
crank arm.

3. EInd of spline shaft is flush with crank arm.

4. Press larger end of V2' rod against end of spline
shaft. It should not move.

5 assisted by 3, examines, cleans, and oils (when necessary)
fuze setter, fuze range indicator, and connections.

3 assists 5 in examining, cleaning, and oiling fuze setter;
checks to see that proper rings are in fuze setter.

6, 8 with gun at zero elevation, remove oil filling plug;
insert liquid release tool and bleed off oil reserve; remove
liquid release tool; connect screw filler, and reestablish
oil reserve; remove screw filler and connections and re-
place oil filling plug.

Note. — If no oil reserve is present, it is necessary to fill
the recoil cylinder before reestablishing an oil reserve.
The oil reserve should not be checked every time the gun
is examined, but only at such intervals as determined by
the battery commander. Normally, checking the oil re-
serve once a week will be sufficient. Never add to an
existing reserve.

7 .checks oil level of remote control system and replenishes
oil if necessary.
AC supervises 9, 10, 11, 12 in preparing ammunition for
firing; sees that all rounds are properly crimped, loose
fuzes staked, corrosion removed from rounds, lot num-

17-18 ANTIAIRCRAFT ARTILLERY FIELD, MANUAL

bers segregated, the emplacement cleared of obstacles,
and ammunition dispersed and provided with protection.
9, 10, 11, 12 assist AC in duties as designated.

7 manually traverses gun through 6,400 mils to insure that
it strikes no obstructions and that the traversing mecha-
nism is functioning properly; traverses gun a few mils in
opposite direction to determine that there is no excessive
backlash.

2 elevates gun manually to maximum elevation; cleans and
oils elevating rack: Caution: Leave elevation rack free
of oil under sandy or dusty conditions.

1, 6 with gun at maximum elevation, place wrench on gun
jack screw and jack gun out of battery approximately 2
inches; retract gun jack screw to original position and if
gun fails to return to battery, direct 2 to depress gun; if
gun does not return to battery by the time it has been
depressed to 710 mils, charge gas pressure into recupera-
tor cylinder to 830 pounds per square inch.

2 elevates gun to maximum and then depresses (gun should
elevate and depress with equal effort) ; with 7, examines
gun junction box.

7 with 2, examines gun junction box.

■ 18. REPORT.
GC commands: REPORT.

G reports to GC, "Breech in order," or reports any defects

he cannot remedy without delay.
2 reports to GC, "Elevation in order," or reports any defects

he cannot remedy without delay.

5 reports to GC, "Fuze setter in order," or reports any
defects he cannot remedy without delay.

6 reports to GC^ "Oil reserve and gas pressure in order,"
or reports any defects he cannot remedy without delay.

7 reports to GC, "Azimuth in order," or reports any defects
he cannot remedy without delay.

AC reports to GC, "Ammunition in order," or reports any
defects he cannot remedy without delay.

90 -MM ANTIAIRCRAFT GUN ON MlAl MOUNT

■ 19. CHECK ORIENTATION.

GC commands: CHECK ORIENTATION; designates orient-
ing point; checks level of gun— if necessary, directs G,
7, 8 to relevel gun; checks to see that power plant switch
is in the OFF position (power plant may be running).

G if directed by GC, loosens auxiliary leveling screw;
tightens screw again when gun has been leveled.

7, 8 if directed by GC, level mount by means of leveling
jacks; call "Level" when gun is level.

G removes firing mechanism from breechblock.

8 places vertical cross hair across muzasle of gun.

Figure 14. — ^Indicator regulator.

GC commands: CHECK AZIMUTH ORIENTATION; gives 7
correct azimuth to orienting point; supervises 7 in set-
ting correct azimuth on indicator regulator after gun has
been laid on orienting point.
G sights through hole in breechblock bushing and lines up
vertical cross hair on muzzle with orienting point by giv-
ing directions to 2 and 7 to elevate or depress and traverse
gun as necessary; calls, "Hold" when gun is on orienting
point.

2 elevates or depresses gun as directed by G.

7 traverses gun right or left as directed by G; when gun is
on orienting point as indicated by G, raises sliding cover
on left side of azimuth indicator; turns toothed wheel

554277"— 43 5 31

ANTIAIRCRAFT ARTILLERY FIELD MANUAL

(A) (fig. 14) until mechanical (outer) pointer reads azi-
muth given orally by GC; checks lagmeter to see that it is
in ZERO position; if necessary, removes cover cap under
sliding cover and turns slotted shaft (B) (fig. 14) until
lagmeter is zeroed (a small screw cover must be removed
before this adjustment can be made) ; checks collimation
of azimuth direct-fire sight.

Caution.— Never attempt to zero lagmeter mechanically
while data transmission system is energized.
G replaces firing mechanism in breechblock.

GC commands: CHECK ELEVATION ORIENTATION.
G sets gunner's quadrant at 800 mils and places it on level-
ing plates on top of breech ring; directs 3 to elevate gun
until level bubble in gunner's quadrant is at center posi-
tion; calls, "Hold" when bubble is centered.

Note. — The last movement of the gun should be in
elevation.

2 elevates gun until G calls, "Hold"; raises sliding cover on
left side of elevation indicator; turns toothed wheel (A)
(fig. 14) until mechanical (outer) pointer reads 800 mils
elevation; checks lagmeter to see that it is in the ZERO
position — if necessary, removes cover cap under sliding
cover (on left side of indicator regulator) and turns
slotted shaft (B) (fig. 14) until lagmeter is zeroed (a small
screw cover must be removed before this adjustment can
be made) ; checks collimation of elevation direct-fire
sight.

Caution. — Never attempt to zero lagmeter mechanically
while data transmission system is energized.

90-MM ANTIAIRCRAFT GtJN ON MlAl MOUNT

FIGURE 15. — ^Puze setter, M13.

GC commands: CHECK FUZE SETTER ORIENTATION.
5 turns adjusting handwheel to set mechanical pointer at

a definite value, such as 14; directs 1 and 3 to insert

round in fuze setter and set the fuze.
1 Inserts round in fuze setter; with right hand keeps

steady pressure on base of cartridge case and with left

hand trips the release lever.
3, as soon as 1 trips release lever, turns setting crank to

set fuze; when setting crank comes to a stop, calls,

"Set."

1 when 3 calls, "Set," removes round from fuze setter.

5 compares reading of the set fuze with the reading of
the mechanical pointers on the fuze indicator — if there
is a discrepancy, verifies it by setting at least two addi-
tional fuzes; unscrews and removes glass window (Y)
(fig. 15) from face of fuze indicator, loosens six retaining
screws on the fuze rani^e scale clamping ring and slips
fuze range scale around under clamping ring until the
average value that was actually set on fuzes is opposite
the mechanical index; sets not less than two new fuzes

19-20 ANTIAIRCRAFT ARTILLERY FIELD MANUAL

at any desired setting; if check is correct, tightens six
retaining screws on clamping ring; operates through a
complete cycle to be sure that dials do not bind at any
place; replaces window.

Note. — When checking orientation of the . fuze setter
the fuzes should he set under the same conditions as
when they are set during firing; that is, they should he
set at the same speed, with the same pressure on the
round as under firing conditions.

m 20. CHECK SYNCHRONIZATION.

GC commands: CHECK SYNCHRONIZATION.
2 sees that motor switch is OFF at gun junction box, and
that transfer valve plunger is OUT; sets selector switch
on elevation indicator on AUTOMATIC.
7 sees that transfer valve plunger is OUT; sets selector
• switch on azimuth indicator on AUTOMATIC.

GC verifies that selector switches are on AUTOMATIC, trans-
fer valves are OUT, and power switch on generator is
on OFF position; directs power plant operator to start
generator and idle until warm, set generator voltage to
the minimum possible by ' turning rheostat on power
plant control panel clockwise to stop, then close power
plant switch to energize system, run generator speed
up to 1200 rpm, and increase voltage by means of the
rheostat until voltage at director reads approximately
115 volts; secures quadrant elevation, azimuth, and fuze
range values from the director and gives the informa-
tion to 2, 7, and 5, respectively.
2 raises sliding cover on right side of elevation indicator;
after power has been turned on, slowly turns selector
switch to MANUAL; operates the gun manually until
value of quadrant elevation received orally from GC is
indicated by mechanical (outer) pointer of the elevation
indicator; raises sliding cover on left side of elevation
indicator and turns slotted shaft (E) (fig. 14) until
electrical (inner) pointer matches mechanical (outer)
pointer; sets selector switch at AUTOMATIC; directs 7
to turn on motor switch at gun junction box.

90 -MM ANTIAIRCRAFT GUN ON MIA 1 MOUNT

7 raises sliding cover on right side of azimuth indicator;
after power has been turned on, slowly turns selector
switch to MANUAL; operates the gun manually until
value of angle of train received orally from GC is indi-
cated by mechanical (outer) pointer of azimuth indi-
cator; raises sliding coyer on left side of azimuth indicator
and turns slotted shaft (E) (fig. 14) until electrical
(inner) pointer matches mechanical (outer) pointer;
sets selector switch at AUTOMATIC; turns on motor
switch at gun junction box when directed by 2.
GC checks oil level as switch on gun junction box is turned
on; if oil level rises, orders motor turned off immediately
and notifies qualified personnel.
2 if lagmeter is not at zero position, turns slotted shaft (D)
(fig. 14) until lagmeter is at zero position; disengages the
handwheel by pushing it toward the muzzle and depresses
the transfer valve plunger.

Note. — If, after the transfer valve plunger is pushed in,
the gun does not come to a synchronous position, or the
gun oscillates, notify qualified personnel.

2 if lagmeter pointer oscillates, directs G to turn adjusting
screw on amplifier marked EL until lagmeter is zeroed
(this balances the amplifier.)

G turns adjusting screw marked EL on amplifier as directed
by 2.

7 if, after power is turned on at gun junction box lagmeter
is not at zero position, turns slotted shaft (D) (fig. 14)
until lagmeter is at zero position; disengages the hand-
wheel by pushing it toward the muzzle, and depresses
the transfer valve plunger.

Note.—//, after the transfer valve plunger is pushed in,
the gun does not come to a synchronous position, or the
gun oscillates, notify qualified personnel

7 if lagmeter pointer oscillates, directs G to turn adjusting
screw on amplifier marked AZ until lagmeter is zeroed.
(This balances the amplifier.)

G turns adjusting screw marked AZ on amplifier, as
directed by 7.

20-21 ANTIAIRCRAFT ARTILLERY FIELD MANUAL

5 turns adjusting handwheel on fuze setter until mechani-
cal pointer indicates the fuze range received orally from
the GC; if necessary, removes cover (X) (fig. 15) on fuze
indicator and turns the slotted shaft until the electrical
(inner) pointer is opposite the mechanical (outer)
pointer; replaces lamp well cover.

Note. — The operations of orienting and synchronizing
are now completed. It should always he rememhered in
orienting and synchronizing that adjusting knobs or
screws should never he forced heyond the mechanical
stops, or moved more than necessary. The glass face on
the azimuth or elevation indicator regulators should not
he removed except in an emergency.

1 21. CHECK OPERATION.

GC commands: CHECK AZIMUTH OPERATION.
7 with the transfer valve plunger in the OUT position
and the handwheels engaged, operates the gun manually
until it is approximately 400 mils from its synchronous
position; disengages handwheels and pushes transfer
valve plunger IN; observes to see if gun comes to rest
at synchronous position with lagmeter at ZERO; makes
same check 400 mils in the opposite direction.

GC commands: CHECK ELEVATION OPERATION.
2 with transfer valve plunger in the OUT position and
handwheels engaged, operates the gun manually until
the gun is approximately 400 mils from its synchronous
position; disengages handwheels and pushes transfer
valve plunger IN; observes to see if gun comes to rest
at its synchronous position with lagmeter at ZERO;
makes same check 400 mils in opposite direction.

Note. — In the above checks, if the gun returns to
its synchronous position, the synchronizer and synchro-
transformer are operating properly. If the gun fails
to return to its synchronous position, call qualified per-
sonnel. If the gun comes to within 150 mils but not
all the way to the synchronous position, the synchronizer
is working properly but not the synchro-transformer.
If the gun does not move at all when the transfer valve

90-MM ANTIAIRCRAFT GUN ON MlAl MOUNT 21-22

plunger is pushed in, the synchronizer,^ and possibly the
synchro-transformer, Is not operating properly. In such
a case, the synchro -transformer can be checked by mov-
ing the gun about 50 mils from its synchronous position
and then seeing if the gun will return to the synchronous
position.

Section V

ANTIAIRCRAFT ARTILLERY DRILL

a 22. TARGET.

GC commands: TARGET.
G opens breech by bearing down on breech operating
handle until breechblock is locked open; latches oper-
ating handle, and assumes a position with feet well
braced, clear of recoil but convenient for loading,
7 turns motor switch at gun junction box to ON. Turns
indicator regulator switch to AUTOMATIC. Disengages
handwheels by sliding them toward muzzle of gun and
then pushes IN on transfer valve. If lagmeter indicates
remote control system is not working properly, returns
to manual operation by raising transfer valve, turning
indicator regulator switch to MANUAL, and engaging
handwheels. Proceeds to match pointers, if operating
on MANUAL.

Caution, — When turning switch from AUTOMATIC to
MANUAL the switch must he turned slowly,

2 turns indicator regulator switch to AUTOMATIC, dis-
engages handwheels by sliding them toward muzzle of
gun and then pushes IN on transfer valve. If lagmeter
indicates remote control system is not working properly,
returns to manual operation by raising transfer valve,
turning indicator regulator switch to MANUAL, and
engaging handwheels. Proceeds to match pointers. If
operating MANUAL. .

Caution, — When turning switch from AUTOMATIC to
MANUAL the switch must he turned slowly,

5 matches pointers on fuze setter.

22-23 ANTIAIRCRAFT ARTILLERY FIELD MANUAL

1 takes round from 6, who has received it from 8, and
inserts It in the fuze setter; presses down on base end
of case with palm of right hand, brings left hand over,
and strikes trip lever on top side of fuze setter.

3 places hand on handle so that as soon as the release lever
is struck by 1, the crank will start; turns handle until it
comes in contact with stop; calls, "Set" to signify that
fuze is set and that roimd can be withdrawn.

1 relieves pressure on case and steps back so as to make
room for 4.

4, as soon as round has been set, moves to No. 1 position

and stands ready to remove the round.
9 removes protective cover from ammunition stacks and

makes ammunition accessible to 8.

1 stands ready to receive another round from 6 and repeat
procedure.

6, 8, 9, lOkeepl supplied with ammunition (6 hands round
to 1 with left hand under rear of round and right hand
on fuze) .

■ 23. FIRE.

Figure 16.

90-MM ANTIAIRCRAFT GUN ON MlAl MOUNT

GC, at command fire, repeats command for first round only,
succeeding rounds being fired without further command;
if a limited number of rounds has been prescribed, he
cautions "(So many) rounds only."
4 without power rammer, removes round from fuze setter
and holds it at loading position at the breech w'here G
can ram it home; as soon as round has been loaded,
pivots on right foot, steps back with left, and stands
ready to remove next round from fuze setter; continues
loading until cease firing is given or the prescribed num-
ber of rounds has been fired.

With power rammer, removes round from fuze setter and
lays it into the breech recess, moving it into the Chamber
far enough to allow G to rotate rammer arm; after G has
positioned the rammer arm, trips the rammer with his
left hand, loading the round; as soon as round has been
loaded, pivots on right foot, steps back with left, and
stands ready to remove next round from fuze setter;
continues loading until cease firing is given, or the pre-
scribed number of rounds has been fired.

G without power rammer, when 4 places round in breech,
rams round "home" with front of his left clenched fist;
when his fist is knocked clear by the rising breechblock,
pivots back on his right foot and fires gun; continues
ramming and firing until cease firing is given, or the
prescribed number of rounds has been fired; kicks empty
cartridge cases clear of platform; in case of misfire, calls
"Misfire" to GC and keeps all cannoneers clear while the
prescribed safety precautions are taken (see par. 40).
With power rammer, when 4 places round into breech
recess, rotates ramming arm into position behind car-
tridge; after 4 has tripped the rammer and the breech-
block has closed, pivots back on his right foot and fires
the gun; continues firing until cease firing is given or
the prescribed number of rounds has been fired; kicks
empty cartridge cases clear of platform; in case of mis-
fire, calls "Misfire" to GC and keeps all cannoneers clear
of recoil while prescribed safety precautions are taken
(see par. 40) .

5 continues to match pointers on fuze setter.

53-24 ANTIAIRCRAFT ARTILLERY FIELD MANUAL

1 continues to load fuze setter; trips release lever and
keeps pressure on base of round as each round is set.

3 turns fuze setter, setting crank each time release lever
is tripped by 1; calls "Set" each time setting crank hits
stopo

2 continues to watch elevation lagmeter pointer, or, if
operating gun manually, continues to match pointers.

7 continues to watch azimuth lagmeter pointer or, if

operating gun manually, continues to match pointers.
6, 8 continue to relay ammunition to 1.

9 clears away empty shell cases from gun emplacement,
being careful to avoid getting behind gun when it is in
action,

10, 11, 12 maintain ammunition supply under supervision

of ACe

AC supervises ammunition squad.

m 24. CEASE FIRING
GC, at command cease firing, repeats the command; sees
that all men remain at post on the alert and that gun
continues to follow target.

2 continues to watch elevation lagmeter pointer, or, if
operating gun manually, continues to match pointers.

7 continues to watch azimuth lagmeter pointer, or, if
operating gun manually, continues to match pointers.

G stops firing and takes hand away from firing lever; if
round remains in bore, signals 4 to remove round; when
4 is in position, opens breech to allow 4 to remove round.

4 stops loading but stands ready to resume loading should
the command fire be given again; if round remains in
bore, removes round at direction of a and passes it back
to the ammunition squad.

AC sets fuzes to SAFE.

5 continues to match pointers on fuze setter.
1 loads fuze setter.

3 sets fuze to have fuze ready for immediate use.

NoTK — After the fuze is set the round is left in the
fuze setter until the command fire is given. Once the
fuze is SET, it will continue to he reset to new values as
new fuze data come from the director.

90-MM ANTIAIRCRAFT GUN Olff MlAl MOUNT 24-26

6, 8 stand ready to resume relaying ammunition to 1.
9 clears away empty cartridg'e cases.
AC supervises the replenishing of ammunition at gun
position.

10, 11, 12 replenish ammunition at gun position.

■ 25. CEASE TRACKING.

GrC, at command cease tracking, repeats command.
2 turns indicator regulator switch to MANUAL, stopping
at the intermediate position for 5 seconds; raises trans-
fer valve and engages hand wheels; remains at post.
7 turns indicator regulator switch to MANUAL, stopping
at intermediate position for 5 seconds; raises transfer
valve and engages handwheels; turns off motor switch;
remains at post.
Gr remains at post,

5 turns mechanical pointer on fuze setter to SAFE; super-
vises 1 and 3 in setting to SAFE all fuzes that have been
SET, checking each fuze as it is removed from fuze
setter; remains at post.
1, 3 assist 5 in setting all SET fuzes to SAFE and returning

them to stacks; remain at posts. -
9 clears away all empty cartridge cases; remains at post.
4, 6, 8 remain at posts.
AC supervises ammunition squad in replenishing stacks at
gun position; checks ammunition to see that it is ready
to be fired; remains at post.
10, 11, 12 replenish ammunition at gun position; remain
at post.

Section VI
DIRECT FIRE DRILL
■ 26, TARGET, DIRECT FIRE.
GC commands: TARGET, DIRECT FIRE; designates target
and sights along gun tube to assist azimuth and elevation
setters to point the gun.
2, with handwheels engaged and transfer valve plunger
in the OUT position, sights through elevation telescope
and operates gun manually to get target on proper range
line; calls "ON" when he is on target.

ANTIAIRCRAFT ARTILLERY FIELD MANUAL

7, with handwheels engaged and transfer valve plunger
in the OUT position, sights through azimuth telescope
and operates gun manually to get target on proper
deflection line; calls "On" when he is on target.

' G without power rammer, opens breech by bearing dow
on breech operating handle; returns breech operating
handle to latched position; after 4 places round in
breech, rams round home with front of left clenched fist;
watches GC for signal to fire.

With power rammer, opens breech by bearing down on
breech operating handle; returns breech operating
handle to latched position; when 4 places round into
breech recess, rotates ramming arm into position behind
cartridge; after 4 has tripped the rammer and the
breechblock has closed, pivots back on his right foot
and watches GC for signal to fire.
4 without power rammer, receives round from 1 and holds
it in the loading position at the breech where G can
ram it "home", as soon as round has been loaded, steps
back to receive the next round from 1.
With power rammer, receives round from 1 and lays
it into the breech recess, moving it into the chamber far

Figure 17.

90-MM ANTIAIRCRAFT GUN ON MlAl MOUNT 26-27

enough to allow G to rotate rammer arm; after G has
positioned the rammer arm, trips the rammer with his
left hand, loading the round; as soon as round has been
loaded, steps back to receive the next round from 1.
1 relays ammunition to 4.

6 relays ammunition to 1.

8 relays ammunition to 6.

3 takes post about 5 yards away from gun, at right of
elevation setter, to observe and spot bursts.

5 takes post about 5 yards away from gun, at left of
azimuth setter, to observe and spot bursts.

9 removes protective covers from ammunition stacks and
makes ammunition available to 8.

■ 27. PIRE.

GC gives estimated range to 2 and estimated lateral lead in
mils to 7.

2 tracks target until he has target on correct range line
as given by GC; indicates he is on target by calling
''Elevation"; after each shot, makes correction, resights
target, and calls "Elevation." .

7 tracks target until he has target on correct mil lead line,
as given by GC; indicates he is on target by calling "Azi-
muth"; after each shot, makes correction, resights target,
and calls "Azimuth."

GC commands: FIRE, as soon as 2 and 7 call "Elevation"
and "Azimuth."

G, after command fire has been given by GC and both
trackers have indicated they are on target, pulls firing
lever to fire gun; kicks empty cartridge cases clear of
platform; continues to fire succeeding shots as soon as
2 and 7 call "Elevation" and "Azimuth" for each shot, or
until GC commands : CEASE FIRING. '

4 continues to serve rounds to the breech.
^ 1, 6, and 8 continue relaying ammunition.

3 spots bursts; calls "Over," "Short," or "Hit," as the case
may be.

5 spots bursts; calls "Right,'"' "Left," or "Hit," as the case
may be. '

9 clears away empty shell cases.

27-29

ANTIAIRCRAFT ARTILLERY FIELD MANUAL

10, 11, 12 replenish ammunition supply at gun position.
AC supervises ammunition squad.

■ 28. CEASE FIRING.

GC commands: CEASE FIRING, when target has been dis-
posed of. He may then assign a new target, have the
men remain on the alert at their positions, or may com-
mand: CEASE TRACKING.
G ceases nring; stands ready to resume firing should a new
target be assigned; if unfired round remains in bore,
keeps all cannoneers clear of recoil.
4 ceases loading; stands ready to resume loading.
1, 6, and 8 stand ready to continue relaying ammunition.

2 continues tracking target in elevation; if target has been
hit, keeps sight on target until new target is assigned.

7 continues tracking target in azimuth; if target has been
hit, keeps sight on target until new target is assigned.

3 and 5 continue to act as observers.
9 clears away empty cartridge cases..

10, 11, and 12 replenish ammunition at gun position,
AC supervises ammunition squad.

1 29. CEASE TRACKING.

GC commands: CEASE TRACKING.
G remains at post; if unfired round remains in bore, directs
4 to remove round, and opens breech when 4 is in posi-
tion.

4 remains at post; if unfired round remains in bore, re-
moves round at direction of GC and passes round back
to 1.

1, 6, and 8 return ammunition to stacks; remain at posts.

2, and 7 cease tracking; remain at posts.
3 and 5 remain at posts.

9 clears away empty cartridge cases.
10, 11, 12 replenish ammunition at gun position.
AC supervises ammunition squad.

CHAPTER 4

NOTES ON MATERIEL

_ „ , Paragraphs

Section I. Emplacement 30-31

n. Direct fire sights ----""""""11""!™ 32-39

Section I
EMPLACEMENT

Figure 18.

■ 30. Description.— Figure 18 is a schematic diagram of the
90-mm AA gun Ml on Mount MlAl in the traveling position.

BOGIE SECURING BOLT .
ENGAGING EYE HOOK

BOGIE ENGAGING EYE

ENGAGING EYE
OPERATING HANDLE

ANTIAIRCRAFT ARTILLERY FIELD MANUAL

The cross sectioning denotes the bogie frame, pedestal, and
trail. From the diagram it can be seen that the pedestal and
trail are underneath the bogie frame.

Figure 20.

The pedestal and trail are secured to the bogie frame by two
engaging eye hooks (fig. 19), located in the rear of the bogie
frame, which engage the bogie engaging eyes, and by two se-
curing bolts, attached to the trail, that swing up into slots
in the front part of the bogie frame.

90- MM ANTIAIRCRAFT GUN ON MlAl MOUNT

The trail and pedestal are held rigidly together at one of two
positions by the trail hinge shaft and the trail lock. In figure
20 the trail is in the upper or traveling position.

The bogie consists of an eccentric axle (fig. 21) which can
best be described as a main axle (bogle axle) with an axle
crank welded to each end. Each axle crank has a wheel
spindle about which the wheel can revolve.

BOGIE DOWN

Figure 22.

Mounted on the bogle axle is the bogie frame (fig. 22.) The
bogie frame is free to rotate about the bogie axle and always
remains in a horizontal position. By rotating the bogie axle
about the wheel spindles (wheel axles) the bogle frame Is
raised or lowered. Likewise, the pedestal is raised or lowered
since it is hung underneath the bogie frame by the bogie eye
hooks and bogie securing bolts.

Attached to the bogie frame are two counterpoise cylinders
(fig. 23) which assist in raising and lowering the bogie frame
to and from the traveling position and act as shock absorbers
when the gim is traveling.

ANTIAIRCRAFT ARTILLERY FIELD MANUAL

BOGIE DOWN

Figure 23.

COUNTERPOISE CYLINDER

Figure 24,

90 -MM ANTIAIRCRAFT GUN ON MlAl MOUNT 30

Each counterpoise cylinder consists of a connecting rod,
clutch rod. two groups of three springs each, and a compres-
sion screw. One end of the connecting rod is attached to the
axle crank and the other end is attached to the clutch rod.
When the gun is emplaced, the bogie axle rotating about the
wheel axle pulls on the connecting rod which in turn pulls the
clutch rod within the counterpoise cylinder (fig. 24) so that
the counterpoise gear box, with the compression' screw, can
be fastened over the end of the counterpoise cylinder. The
weight of the gun will rotate the bogie axle far enough to
compress the counterpoise springs to such an extent that the
counterpoise gear boxes can be engaged. At this point the
forces exerted by the weight of the gun and the compressed
springs are equal, and it is necessary to turn the compression
screws to force the bogie axle down until the pedestal is
resting firmly on the ground.

BOGIE BUFFER

Figure 25.

To prevent the mount from emplaclng itself while traveling,
there is an axle lug welded to the bogie axle, which is held
firmly in place between the bogie bumper and bogie bufifer
(fig. 25). To emplace the gun it is necessary to remove the
bogie buffer from the path of the axle lug so that the bogie
axle can rotate about the wheel axle.

30-31 ANTIAIRCRAFT ARTILLERY FIELD MANUAL

AXLE LUG

BOGIE BUFFER

PiGUBE 26.

The bogie buffer (fig. 26) consists of a cylinder pivoted to
the bogie frame, a plunger, a spring, and a retracting hand-
wheel. In the traveling position the spring holds the
plunger against the axle lug. To emplace the gun, it is
necessary to turn the handwheel to retract the plunger from
the axle lug and swing the buffer out of the way.

■ 31. Emplacement With Prime Mover. — a. In figure 27 the
gun is in the traveling position, the bogie axle is approxi-

90 mm MOUNT - TRAVELING POSITION

90 -MM ANTIAIRCRAFT GUN ON MlAl MOUNT

mately over the wheel axles, the bogie buffer is holding the
axle lug against the. bogie bumper, and the counterpoise
clutch rods are extending beyond the. open eiid of the coun-
terpoise cylinders.

b. To emplace the gun, the electric brakes are applied to
prevent the bogie wheels from turning and the prime mover
pulls forward several feet. This action pulls, on the trail,
bogie frame, and bogie axle, and causes the bogie axle to
rotate forward and down about the wheel axle. As the bogie
axle moves forward, it forces the axle lug against the bogie
buffer plunger and forces the plunger into the cylinder, com-
pressing the spring. This permits the haridwheel on the
bogie buffer to be run down to hold the buffer plunger in
the retracted position. The prime mover then backs up
several feet, causing the axle lug on the bogie axle to be
rotated away from the buffer plunger so that the buffer can
be tipped out of the path of the axle lug.' If the prime mover
is again pulled forward, the bogie axle rotates about the
wheel axles and lowers the pedestal to the ground. This
action compresses the counterpoise springs and since the
springs act to raise the mount to the traveling position, it is
necessary to engage the counterpoise gear boxes over the
ends of the cylinder to keep the springs compressed before
uncoupling the trail from the prime mover.

c. With the counterpoise gear boxes engaged, the prime
mover is uncoupled from the trail, the platforms removed
from their brackets on the trail, the transom cap unfastened
from the gun tube, and the tube elevated to maximum ele-
vation (fig. 28) . The tube is elevated at this point to transfer
the preponderance of weight of the gun to the rear of the
pedestal to facilitate lowering the trail. With' the tube ele-
vated, the mount is completely crushed by turning the cranks
on the counterpoise cylinders in the direction of BOGIE
DOWN, until the pedestal is resting firmly on the ground
and none of the weight is supported by the bogie (fig. 29) .
The trail is then lowered from its upper position as shown
in figure 29 to the lower position as shown in figure 30.
To lower the trail (fig. 30) , the bogie securing bolts are disen-
gaged from the front of the bogie, the nuts on the engaging
eye hook are loosened, the swing bolt from the trail lock

ANTIAIRCRAFT ARTILLERY FIELD MANUAL

90 -MM ANTIAIRCRAFT GUN ON MlAl MOUNT

31-33 ANTIAIRCRAFT ARTILLERY FIELD MANUAL

rocker arm is unfastened, and the rocker arm pulled up.
This unlocks the trail from the front of the pedestal and
allows the trail to be lowered until it is in the same plane
with the pedestal, where it is locked in the lower position by
pulling down on the trail lock rocker arm and securing it with
the swing bolt.

d. After the trail is lowered, the bogie engaging eye operat-
ing handles (fig. 31) are pushed in to disengage the eyes from
the eye hooks and the bogie is rolled out to the end .of the
trail. This accomplishes emplacement with the exception of
leveling which is taken up elsewhere in the manual.

Section II

DIRECT FIRE SIGHTS

■ 32. General. — Antiaircraft artillery may be used effectively
against ground and water-borne targets. For this purpose
direct-fire telescopic sights have been provided for the 90-mm
gun in firing at ranges up to 3,000 yards. One telescope is
used for tracking in azimuth and one for tracking in elevation.

■ 33. Description. — a. Mounts.— yioxmi M28 is used for
mounting the elbow telescope M24 to the left side of the gun.
It is attached to the top carriage above the azimuth hand-
wheels and rotates with the gun in azimuth only. Telescope
mount T65 is. used for mounting elbow telescope M26 to the
right side of the gun. It is attached to the side of the cradle,
back of the indicator regulator; it moves with the gun in
azimuth as well as in elevation.

b. Telescopes. — Except for their reticle patterns the two
elbow telescopes, M24 for azimuth and M26 for range, are
similar. Each is a three-power, erect image instrument with
a field of view of 13° 20' or 1/27 of a full circle.

c. Azimuth reticle. — The reticle of the azimuth telescope has
a single horizontal scale marked in mils lead (fig. 32). The
minimum graduation is 5 mils and the numbered graduations
are multiples of 10.

d. Range reticle. — Across the bottom half of the range tele-
scope's reticle are seven horizontal range lines for aiming at
the following ranges: point blank, 500 yards, 1,000 yards, 1,500
yards, 2,000 yards, 2,500 yards, and 3,000 yards (see fig. 33) .

90-MM ANTIAIRCRAFT GUN ON MlAl MOUNT

34 ANTIAIRCRAFT ARTILLERY FIELD MANUAL

■ 34. ALiNEMENT..— a. The telescopes are in alinement and
properly adjusted when the line of sight of the telescopes are
parallel to axis of the gun bore, and the horizontal deflection
scale and range lines of the reticles are in the horizontal
position.

&. To check alinement and adjustment of the telescopes,
place the bore sights in the gun and accurately point it at a
celestial body or the most distant distinct point available.
This point should appear on the zero mark on the deflection

RETICLE RQTATtO W
WORM— ~

ELEVATION AQUUSTMENT
— ■ -WORM (HIDDf

*CtAMPiNG SCREW

Figure 34. — ^Telescope M26.

scale of the azimuth reticle and on the center of the zero range
line of the elevation reticle. The horizontal deflection scale
of the azimuth reticle and the range lines of the elevation
reticle should be in a horizontal position. If these conditions
do not exist, one or more of the following adjustments are
made:

(1) The reticle lines are placed In a horizontal position.
A reticle rotation worm screw, secured by a clamping screw,
on top of the telescope's elbow angle is provided for this pur-
pose. (See figs. 34 and 35.) To bring the reticle line to the
horizontal position, loosen the clamping screw; turn the worm.

90 -MM ANTIAIRCRAFT GUN ON MlAl MOUNT

the head of which has a screw driver slot, until the reticle
line Is satisfactorily positioned; then tighten the clamping
screw.

tATgRAt WUSTMEHT

Figure 36.— Telescope mount M28 with telescope M24.

(2) The orienting point must be brought to the zero range
line of the range reticle and to the top of the deflection scale
of the azimuth reticle.

^4-36 ANTIAIRCRAFT ARTILLERY FIELD MANUAL

(a) In the range telescope, raise or lower the point to the
zero range line by loosening thp clamping screw and turning
the elevation adjusting worm (fig. 34) on top of the telescope.
When the adjustment is complete, tighten the clamping
screw.

(&) In the azimuth telescope, raise or lower the orientmg
point to the horizontal line by turning the elevating knob (fig.
35) under the elbow angle.

(3) The orienting point must be centered on the horizontal
line of each telescope. To do this, loosen the two clamping
screws (fig. 35) on the telescope mount, turn the worm be-
tween them until the sight is adjusted accurately, and then
tighten the two collar screws.

Note.— After tightening the clamping screw of any worm ad-
justment, always check to see that alinement has not been altered
by the screw's pressure.

■ 35. Duties of Personnel.— When using direct-fire sights,
only four members of the gun crew remain on the platform.
The fuze setter operator (3) and the fuze range setter (5)
take spotting posts to the right and left, respectively, about
5 yards from the edge of the platform. No 1 moves off the
platform and becomes an ammunition relayer, relaying the
ammunition from 6 directly to 4. Nos. 8 and 6 relay ammu-
nition to No. 1. No. 4 holds each round in readiness at the
breech for the gunner to ram home. The gunner, instead
of firing immediately, waits for the signal from the gun com-
mander to fire. The gun commander gives the signal to fire
the first round only when both azimuth setter and elevation
setter signify they are on target.

■ 36. Tracking.— Manual operation of the gun is required
while using direct-fire sights. The azimuth setter observes
through his telescope with his left eye, following the target by
turning the azimuth handwheel. If necessary, he simulta-
neously twists the telescope's elevation knob with his left hand
to keep the target within the limits of the reticle. The center/
line of this reticle should always point ahead of a moving
target and at a stationary target. The elevation setter ob-
serves through his telescope with his left eye, following the
target in range by turning the elevation handwheels. In

90-MM ANTIAIRCRAFT GUN ON MlAl MOUNT 36-39

tracking targets with the elevation telescope, carry the ver-
tical center of the target on the correct or estimated range
line.

■ 37. Fire Control.— The gun commander estimates the tar-
get speed and range, and calls the lateral lead and range to the
azimuth and elevation trackers. Prom these data the track-
ers set the initial lateral lead and range. As the first and
succeeding shots are fired, they observe the bursts or impacts
and make corrections on their own initiative. They are aided
in their sensings by the sensings of the spotters (3 and 5).
Nos. 3 and 5 observe the bursts and call "Right" or "Left"
for the azimuth observer and "Over" or "Short" for the range
observer. For a full discussion of fire control using direct-
fire sights, see FM 4-110 and FM 4-121 (when published) . ^

W 38. Ammunition.— Armor-piercing shot M77 and projectile
M82 with armor-piercing cap are provided for fire against
armored targets. Both types contain a tracer element for the
observation of fire. In addition, the regular high-explosive
shell M71 for firing against thin-skinned targets is available.

■ 39. Care.— a. There are oil cups on both telescope mounts
for the lubrication of the principal bearing surfaces. Oil is
applied as required by service conditions. Clamp pivots on
the telescope brackets are oiled occasionally with only a few
drops of oil. All excess oil is wiped off to prevent any accu-
mulation of dust and grit.

b. The lenses of the telescope are cleaned only with alcohol
and a camel's-hair brush, and then wiped dry with lens
tissue. The rubber eyeshields are removed occasionally and
washed in warm water.

c. When the telescopes are placed in their mounts, all dust
and grit must be wiped off the contact surfaces of both tele-
scope and mount. The projecting lug of the telescope is fitted
into its mated opening on the mount and the wing nut should
be securely tightened.

d. The elbow telescopes are placed in their carrying case
when not in use. The adapter and eyeshield are pushed alon#
the telescope tube until the shield is flush with the end of
the tube. This prevents the shield from being flattened or
crushed,

CHAPTER 5

SAFETY PRECAUTIONS

■ 40. General. — Safety precautions to be observed for train-
ing are prescribed in AR 750-10 and PM 4-118 (when pub-
lished). The more important safety precautions relating
to the gun section are summarized in the following para-
graphs. These precautions will be followed as closely as the
situation permits, even under combat conditions.

■ 41. Ammunition. — a. All ammunition at the firing point
must be placed so as to be protected against explosion in case
of accident at the gun position. It should be in a dry place
and protected against direct rays of the sun by a tarpaulin
or other suitable covering. Erratic shots and dangerously
high powder pressures may result from overheated ammuni-
tion.

b. No attempt will be made by battery personnel to dis-
assemble the round or fuze. This is dangerous and is strictly
prohibited.

c. If for any reason a round is not fired after the fuze has
been set, the fuze will be reset at SAFE before putting the
round away„

d. In case of a misfire, two attempts are made to fire the
round before opening the breach and removing the round.

e. If a live round cannot be extracted in the normal man-
ner, it is fired, safety precautions permitting. If this is im-
possible, it is removed under the supervision of an officer, a
rammer being used which bears only on the projectile and
provides for clearance around the fuze.

■ 42. Materiel. — a. In coupling or uncoupling the gun with
the prime mover, no one should be between the prime mover
and the lifting bar of the trail. Sudden movements of the
prime mover would crush anyone caught between.

h. In emplacing the gun it is necessary to compress the
counterpoise springs before loosening the nuts of the bogie
engaging eye hooks. This must be done to prevent the
equilibrator cylinder from resting on the bogie frame and
thus supporting the entire weight of the mount less bogie.

90-MM ANTIAIRCRAFT GUN ON MlAl MOUNT 42-43

c. When the leveling packs are manipulated, the auxiliary
leveling screw must be manipulated at the same time to
prevent damage as a result of the auxiliary leveling screw
binding.

d. When preparing the gun for traveling and the mount
is lifted up to permit the bogie buffer cylinder to be rotated
down against the axle lug, the rear outrigger must not be
unpinned from the pedestal to facilitate the operation. When
this is done there is danger of the mount overturning. If
necessary, dirt should be dug out from under the rear out-
rigger instead.

■ 43. Drill and Firing.— a. The gun is unloaded except
when it is being fired or when about to be fired.

b. Members of the gun section always pass in rear of the
gun, clear of the recoil, when going from one side of the gun
to the other.

c. Personnel must keep at a safe distance from the rear
of the breech to prevent injury when the gun recoils.

d. The gunner keeps clear of the firing lever until the
piece has been loaded and is ready to be fired. Care must
be taken to prevent accidental contact with the firing lever
during the loading operation. ° In addition, the gunner makes
sure that he does not fire the piece until he has pivoted on
his right foot away from the rear and to the side of the gun.

e. The gun platform should be kept in such condition
that its surface offers the maximum frictional resistance to
the footgear of personnel. It should be kept free of oil and
grease, and sprinkled with sand during rainy weather. Hob-
nailed shoes should not be worn by personnel on the gun
platform.

CHAPTER 6

DESTRUCTION OF MATERIEL

■ 44. General.— a. Tactical situations may arise when, due
to limitations of time or transportation, it will become im-
possible to evacuate all equipment. In such situations it is
imperative that all materiel which cannot be evacuated be
destroyed to prevent—

(1) Its capture intact by the enemy.

'(2) Its use by the enemy, if captured, against our own or
allied troops,

h. The working principles to be followed are:

(1) Methods for the destruction of materiel subject to
capture or abandonment in the combat zone must be ade-
quate, uniform, and easily followed in the field.

(2) Destruction must be as complete as the available time,
equipment, and personnel will permit. If thorough destruc-
tion of all parts cannot be completed, the most important
features of the materiel should be destroyed, and parts es-
sential to the operation or use of the materiel and which can-
not be easily duplicated, ruined or removed. The same
essential parts must be destroyed on all like units to prevent
the enemy constructing one complete unit from several dam-
aged ones by "cannibalization."

(3) THE BESTRUCTION OE MATERIEL IS A COM-
MAND DECISION TO BE IMPLEMENTED ONLY ON AU-
THORITY DELEGATED BY THE DIVISION OR HIGHER
COMMANDER.

c. To accomplish adequate and uniform destruction of
materiel, it is essential that —

(1) All echelons prepare plans for the destruction of
materiel in the event of imminent capture. Such plans must
be flexible as to the available time, equipment, and personnel.

(2) All echelons be trained to effect the desired destruction
of materiel issued to them. Training will not involve the
actual destruction of materiel.

■ 45. Methods.— -a. The destruction procedures outlined are
arranged in order of effectiveness. Destruction should be
accomplished by method No. 1, if possible. If method No. 1

90-MM ANTIAIRCRAFT GUN ON MlAl MOUNT 45-46

cannot be used, destruction should be accomplished by one
of the other methods outlined, in the priority shown.

b. Whichever method is used, the sequence outlined should
be adhered to. Uniformity of destruction will then be ob-
tained, whether or not the method is carried to completion.

c. Certain of the methods outlined require special tools
and materials, such as TNT and incendiary grenades, which
normally may not be items of issue. The issue of such spe-
cial tools and materials, the equipment for which issued, and
the conditions under which destruction will be effected are
command decisions in each case, according to the tactical
situation.

■ 46. Tube, Breech, and Recoil Mechanism. — a. Sights,^
Detach all optical sights. If evacuation Is possible, carry the
sights; if evacuation is not possible, thoroughly smash the
sights.

b. Method No, 1. — (1) Open drain plug on recoil mecha-
nism, allowing recoil fluid to drain. It is not necessary to
wait for the recoil fluid to drain completely before firing
the gun in (4) below.

(2) Place an armed (safety pin removed) M9A1 antitank
renade, HE, or armed (safety pin removed) M6 antitank

ket in the tube about 6 inches in front of and with the
ve nose end toward the HE shell in (3) below.

(3) Insert an unfuzed HE complete round into the gun and
close the breech.

(4) Fire the gun, using a lanyard at least 100 feet long.
The person firing should be under cover to the rear of the
piece and approximately 20° off the line of fire. Elapsed
time, approximately 2 to 3 minutes.

(5) The danger zone is approximately 200 yards,

c. Method No, 2.— Insert TNT blocks in the bore near the
muzzle and in the chamber of the gun. Close the breech-
block as far as possible without damaging the safety fuze, •

lug the muzzle tightly with earth to a distance of approxi-
ately three calibers from muzzle. Detonate the TNT
rges simultaneously. The following number of 1/2 -pound
TNT blocks will be needed for effective demolition: bore, 3
to 5; chamber, 8 to 10. If it is not possible to plug the bore,
a larger number of TNT blocks will be needed for effective
demolition, 63

46-47 ANTIAIRCRAFT ARTILLERY FIELD MANUAL

d. Method No. 3.~(1) Fire adjacent guns at each other
at point-blank range, using HE or AP shells. Two or more
direct hits from a weapon of the same caliber, on a vital
spot such as the breech mechanism, recoil mechanism, or
tube should adequately destroy the gun. Fire from cover,
using lanyard. Danger space is from 200 to 500 yards.

(2) Destroy the last gun and carriage by the best means
available.

(3) Danger from "cannibalization" is inherent in this
method.

e. Method No. Insert four unfuzed M14 incen-

diary grenades end to end midway in the tube at 0° eleva-
tion. Ignite these four grenades by a fifth equipped with
a 15-second Bickford fuze. Klapsed time, 2 to 3 minutes.

(2) The metal from the grenades will fuse with the tube
and fill the grooves.

■ 47. Carriage.— Whenever possible, artillery carriage de-
struction should be accomplished in conjunction with the
destruction of the tube, breech, and recoil mechanism in
paragraph 46. When this cannot be done, destruction of
the tube, breech, and recoil mechanism will have priority-

a. Method No. 1. — (1) Place two unfuzed, boostered point
detonating HE shells between the right and left wheels and
the bogie. Set shells upright and place a ^2 -pound TNT
block over the booster in each shell. Detonate TNT blocks
simultaneously, using - detonating cord, tetryl nonelectric
caps, and at least 5 feet of safety fuze. Electric detonation
methods may be used if available.

(2) If possible, combine this method with the destruction
of the tube, breech, and recoil mechanism in paragraph 46c,
using simultaneous detonation.

b. Method No. 2.— (1) Place six y2-pound TNT blocks in
the battery receptacle on the trail. Detonate TNT charges
simultaneously, using detonating cord, tetryl nonelectric
caps, and at least 5 feet of safety fuze. Electric detonating
methods may be used if available. i

(2) This method of destruction may be combined wij|
destruction of the tube, breech, and recoil mechanism, out-
lined in paragraph 46c, by simultaneous detonations.

c. Method No. 3. — See paragraph 46c?.

90-MM ANTIAIRCRAFT GUN ON MlAl MOUNT

48-49

■ 48. TRUCKs.---a. Method No. i.— Remove and empty port-
able fire extinguisher. Puncture the fuel tank. Open the
hood and place a 2 -pound charge of TNT on top of the
clutch housing. Place another 2-pound charge on the left
side of the engine as low as possible. Insert tetryl non-
electric caps with at least 5 feet of safety fuze in each charge.
Ignite the fuzes and take cover. Elapsed time, 1 to 2 min-
utes if charges are prepared beforehand and .carried in the
vehicle. In this case, keep the caps and fuzes separated
from the charges until used.

5. Method No. 2.— Remove and empty the portable fire
extinguisher. Puncture the fuel tank. Smash all- vital ele-
ments, such as distributor, carburetor, radiator, engine block,
air and oil cleaners, generator, control levers, crankcase, and
transmission, with a heavy ax, pick, or sledge. Pour spare
gasoline, oil, or distillate over entire unit and ignite.

c. (1) Whenever time and materials are available, com-
bine the vehicle destruction in a and b above with the arma-
ment destruction in paragraph 46.

(2) If possible, detach and evacuate all machine guns
mounted in vehicles prior to destroying the vehicle.

■ 49. Pneumatic Tires.— a. General— (1) Rubber is such a
critical item, that whenever materiel is subject to capture or
abandonment, an attempt to destroy pneumatic tires must
always be made, even if time will not permit destruction of
the remainder of the vehicle.

(2) With adequate planning and training, however, the
destruction of tires may be accomplished in conjunction with
destruction of the vehicle without increasing the time nec-
essary.

h. Method No. l.—d) Ignite an M14 incendiary grenade
under each tire.

(2) To insure the best results when this method is com-
bined with the destruction by TNT of the gun and carriage
, and of the trucks, be certain that the incendiary fires are
Well started before detonating the TNT.

br caliber .50 machine gun fire. (If time permits, deflate
the tires before damaging them.) Pour gasoline on the tires,
dousing each one, and then ignite.

Damage the tires with an ax, pick,

49-51 ANTIAIRCRAFT ARTILLERY FIELD MANUAL

(2) When used in conjunction with truck destruction, the
ensuing fire will usually destroy the vehicle adequately.

■ 50. Cables. — All cables from the junction box to the gun
are heaped in a pile, doused with gasoline, and burned. If
time is available, cut the cable into short lengths before
burning. Smash all receptacles and plugs.

■ 51. Ammunition. — a. General. — (1) Time will not usually
permit the destruction of all ammunition in forward combat
zones.

(2) When sufficient time and materials are available, am-
munition may be destroyed as indicated in h and.c below.
At least 30 to 60 minutes will be required to destroy ade-
quately the ammunition carried by combat units.

(3) In general, the methods and safety precautions out-
lined in TM 9-1900 should be followed whenever possible.

b. Unpacked complete round ammunition. — (1) Stack am-
munition in small piles. Stack or pile most of the available
gasoline in cans and drums around the ammunition. Throw
onto the pile all available inflammable material such as
rags, scrap wood, and brush. Pour the remaining available
gasoline over the pile. Sufficient inflammable material must
be used to insure a very hot fire. Ignite the gasoline and
take cover.

(2) An alternate method is by sympathetic detonation,
using TNTo Stack the ammunition in two stacks, about 3
inches apart, with the fuzes in each stack toward each other.
Place TNT charges between the stacks. Use a minimum
of 1 pound of TNT per four to five rounds of ammunition.
Detonate all TNT charges simultaneously from cover.

c. Packed complete round ammunition. — (1) Stack the
boxed or bundled ammunition in small piles. Cover with all
available inflammable materials, such as rags, scrap wood,
brush, and gasoline in drums or cans. Pour gasoline over
the pile. Ignite the gasoline and take cover. (Small-arms
ammunition must be broken out of the boxes or cartons
before burning.) j

(2) (a) The destruction of packed complete round am-
munition by sympathetic detonation with TNT is not advo-
cated for use in forward combat zones. To insure satisfac-

90-MM ANTIAIRCRAFT GUN ON MlAl MOUNT 51

tory destruction involves putting TNT in alternate cases or
bundles of ammunition, a time-consuming job.

(&) In rear areas or fixed installations, sympathetic deto-
nation may be used to destroy large ammunition supplies if
destruction by burning is not feasible. Stack the boxes,
placing in alternate boxes in each row sufficient TNT blocks
to insure the use of 1 pound of TNT per four to five rounds
of ammunition. Place the TNT blocks at the fuze end of
the rounds. Detonate all TNT charges simultaneously. See
FM 5-25 for details or demolition planning and procedure.

Appendix

LIST OF REFERENCES

Cleaning, preserving, lubricat-
ing, and welding materials
Defense against chemical at-
tack

Gunnery for aintiaircraft artil-
lery

Formations, inspections, AAA__

Fire control, A A guns

90-MM antiaircraft gun mate-
riel Ml and MlAl

Reference data

Remote control system M2

Safety precautions in firing

TM 9-850.

FM 21-40.

FM 4-110.
FM 4-120.

FM 4-121 (when published)

TM 9-370 and TM 9-1370.
FM 4-118 (when published)
TM 9-1642 and TM 9-2642.
AR 750-10.

INDEX

Paragraph

Amplifier, balancing 20

Axle lug__ . 30

Ammunition, for direct fire 38

Bogie engaging eye hooks 30

Bogie securing bolts ■_ 30

Bogie axle 30

Bogie buffer cylinder. _~ 30

Counterpoise cylinders 30

Counterpoise gear box 30

Commands:

CalPcff-,^ ' 9

Change order 10

' Cease firing _ 24,28

Cease tracking _._ 25 29

Check azimuth operation '21

Check azimuth orientation____ 19

Check elevation cperation 21

Check elevation orientation . 19

Check fuze setter orientation _ . 19^

Check operation. , 21

Check orientation ig

Check synchrorization 20

Count off 3

Details posts . 12

Examine gun . 17

Fall in ____ 7

Fire — _ 23,27

Report ^ 13

Rest , ~ 12

Target _"_ 22

Target, direct fire . 26

Decontamination j 2

Drill procedure, explanation of_ 5

Drill procedure, instructions- g

Destruction of materiel :

Ammunition __; 51

Cables 50

Carriage , 47

General : 44

Methods : ~ 45

Sights 46

Tires 1 49

Trucks 48

Tube, breech, and recoil mechanism 46

Emplacement :

Description 30

With prime mover 14,31

Without prime mover 13 .

Pire control, with direct-fire sights. 37

3un section- 3

Page
33
45
59

45
45
45
45

45
45

6
6

40, 44
41,44
36
31
36
/32
33
36
31
34
6
8
28
5

38, 43
30
8
37
41

1
4
4

66
66
64
62
62
63
65
65
63

45
16, 50

9
59

INDEX

March order: Paragraph

With prime mover , 16

Without prime mover 15

Oil reserve ■ 17

Personnel, designation 3

Personnel, duties 4, 35

References App .

Safety precautions :

Ammunition 41

Drill and firing ^ 43

Materiel ' 42

Telescope mounts __ 33

Telescopes :

Alinement 34

Care 39

Description 33

Reticles 33

Tracking, with direct-fire slights _ 36

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IMPLEMENTATION GRANTS PASS SUSTAINABILITY AND ENERGY ACTION PLAN EMISSIONS REDUCTION POTENTIALS BY GENERAL PROJECT The timeline included in this Plan is only one model for reaching emissions goals, meant to serve as a u…
Medford — Transportation System Plan 2018-2038 p.236
• With substantial upgrading of the track and signa l system , the rail line connecting the eight Rogue Valley com munities is well suited to serve as the backbone of an effective com muter transportation sy stem for…

Epstein Files

EFTA00603443 — 1044C-54 Series II TELEHANDLER
Model 1044C-54 Series II TELEHANDLER Rated Capacity 10.000 lb14,536 kg) Maximum Lift Height 54 ft 116.5 ml Frame Leveling 10 degrees Lift Speed (boom retracted, no load) Up: 15.6 sec Down: 14.6 sec Boom Speed (no load) E…
EFTA01810260 — 54.1-4202. Penalties for violation of the
54.1-4202. Penalties for violation of the provisions of this chapter Any person convict- ed of a first offense for willfully violating the pro- visions of this chapter shall be guilty of a Class 2 misdemeanor. Any person…
EFTA01122147 — OWNER'S MANUAL
OWNER'S MANUAL M101B5 / MlOW5 Marine Subwoofer Thank you for choosing a IL Audio Marine Sub woofer. With proper installation, your new speaker will deliver years of listening pleasure. We strongly recommend that you have…

Federal Writers' Project

[The Alms Massacre]
117111110411 Dec. 3, 3, 1937 The Alms Massacre Our family left Sherman, Texas Sept., 1879 for Arizona, where one of my uncles was supposed to be living. We came by Deming where we were warned that the Indians were out an…
[Spark, The Mighty Man]
7F7 V44-erwiteArt..... SPARKS, THE MIGHTY MAN January 4, 1921 (My 19th birthday) went to the recruiting station on Bast 23rd St. and wenlisted in the United States Marine Corps, for a period of four years. Tomorrow I go …
[Andrew Johnson]
k?4.4_,C4 Forms to be /iMed out for Each Interview FOLKLORE NEW YORK STATE New York City NAME OF WORKER FORMA Circumstances of Interview Levi C. Hubert ADDRESS 353 West 118th St. Manhattan. DATE November 28, 1938 SMUT II…

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US Artillery Delivered to Ukraine Is More Than Guns, It Is a Game-Winning Change From the Present
On the night of February 11-12, 1951, three veteran Chinese Communist armies (39th, 40th, and 66th) and a North Korean corps kicked off the Chinese Army’s spring offensive against UN forces in Korea. The initial onslaugh…
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Fox News Flash top headlines are here. Check out what's clicking on Foxnews.com. The 155 mm howitzer round is one of the most requested artillery munitions of the war in Ukraine. Already the U.S. has shipped more than 1.…