[Browning Machine Gun, Caliber .50, M2, Water-Cooled, and Mounts]
[From the U.S. Government Publishing Office, www.gpo.gov]

\X)	9-226
" NON-CIRCULATING
WAR DEPARTMENT
TECHNICAL MANUAL
BROWNING MACHINE GUN, CALIBER .50, M2, WATER-COOLED, AND MOUNTS
Li w iiHit i
Changes
No. 1
TM 9-226
*c 1
WAR DEPARTMENT, Washington, May 16, 1942.
TECHNICAL MANUAL
BROWNING MACHINE GUN, CALIBER .50, M2, WATER-COOLED, AND MOUNTS
TM 9-226, December 10, 1940, is changed as follows:
25. Care and cleaning of gun.—a. Cleaning bore.— (1) Disassemble groups from gun. The bore should be cleaned thoroughly with rifle bore cleaner. This cleaner is a combination solvent and preservative which is issued for use by troops in the field for cleaning small arms. For specifications of cleaners, oils, and rust-preventive compounds, see TM 9-850 and SNL K-l.
(a)	To use rifle bore cleaner, saturate a clean patch with rifle bore cleaner and push it back and forth through the bore of the barrel by means of a cleaning rod. Repeat the operation with clean patches two or three times, and then use a clean dry patch to remove all the cleaner before applying the prescribed lubricating oil, preservative, light.
(6)	Lubricating oil, preservative, light (if unavailable, lubricating oil for aircraft instruments and machine guns), should be used to protect the bore if the weapon is to remain out of service for several days. For long-time storage, rustpreventive compound, light, should be used in place of oil. See d below. However, before use, the gun should be cleaned thoroughly and reoiled with lubricating oil, preservative, light.
(2)	When rifle bore cleaner is not available, proceed as follows: Place barrel, muzzle down, in a vessel containing hot water and issue soap or a soda ash and water solution (I1/? tablespoons per pint of water), or, lacking these, hot or cold water alone.
*******
c.	Cleaning tripod.
*******
(2)	For the antiaircraft machine-gun mount, caliber .50, M2, use lubricating oil, preservative, light. If not available, use lubricating oil for aircraft instruments and machine guns. Lubricate the slide of the recoil mechanism through the oil hole located in the top of the slide. The slide should be lubricated every
*These changes supersede section III, Training Circular No. 71, War Department, 1941.
459914°—42	1
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C 1	TECHNICAL MANUAL
2 hours during continuous firing. The elevating and traversing screw should be oiled with a few drops of oil every day.
d.	Preparation for storage.
*******
(2) Apply rust-preventive compound, light, to all metal parts of the gun. Rust-preventive compound, light, is to be used on guns for both temporary and permanent storage. It may be applied with a brush or by dipping. In applying, heating is not necessary except in very cold temperatures. Application of the rustpreventive compound * * * whenever the weapon is not in use.
*******
g. Lubricating oil.— (1) (a) Proper oiling is second in importance only to intelligent cleaning. It is a vital necessity * * * anj the ways of the belt feed slide.
(6) Lubricating oil, preservative, light, has preservative as well as lubricating properties, and care should be taken to use it where permissible. If lubricating oil, preservative, light, is not available, lubricating oil for aircraft instruments and machine guns may be used. However, the latter oil must not be considered as a preservative. In a warm, humid atmosphere, metal surfaces covered with lubricating oil for aircraft instruments and machine guns will not be suitably protected against rusting. Lubricating oil, preservative, light, should always be used for preserving the bore between firings, after the barrel has been cleaned.
Note.—All guns which are not protected with rust-preventive compound must be inspected periodically for signs of rust, the interval between inspections depending upon local climatic conditions.
(2)	If the gun is to be fired in areas where the temperature is 45° F. or above, oil, sperm, should be used when available. When not available, engine oil, SAE 10, or any light grade machine oil may be used in an emergency.
(3)	On all types of machine guns, when operated in areas where the temperature is below 45° F., oil, lubricating, for aircraft instruments and machine guns, should be used.
(4)	For lubricating the M2 mount, sperm oil (U. S. Army Spec. No. 2-45A) or aircraft instrument and machine-gun lubricating oil should be used under the same conditions as in the case of the gun. If either of these is not available, any suitable motor oil or machine oil may be used.
[A. G. 062.11 (11-26—41) (3-20-42).] (C 1, May 16, 1942.)
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TM 9-226 BROWNING MACHINE GUN, CALIBER .5 0, M2 Cl
26. Method of filling oil buffer.—Remove the oil buffer tube filling screws from the base of the buffer tube. Use the oil buffer filling oiler filled with aircraft instrument and machine-gun lubricating oil. Start the flow of oil by pressing on the base of the oiler. While the oil continues to pour * * * when the buffer tube is completely full.
[A. G. 062.12 (11-26-41).] (C 1, May 16, 1942.)
By ORDER OF THE SECRETARY OF WAR J
Official :
J. A. ULIO,
Major General,
The Adjutant General.
G. C. MARSHALL, Chief of Staff.
I
3
U. S. GOVERNMENT PRINTING OFFICE: 1942
TEXAS STATE COLLEGE FOR WUMLH
LIBRARY
TM 9-226
-rEUS W0M®
C 2
TECHNICAL MANUAL
BROWNING MACHINE GUN, CALIBER .50, M2, WATER-COOLED, AND MOUNTS
Changes 1	WAR DEPARTMENT,
No. 2 j	Washington, July 30, 1942.
TM 9-226, December 10,1940, is changed as follows:
7.	Description of antiaircraft machine-gun mount, caliber .50, M2.
*******
Z>. (5) Adjustment of recoil mechanism (fig. 7).— (a) With the upper buffer recoil spring at its assembled length (2.09 inches) screw in the counter-recoil spring adjusting plug until its front face is 7%2 inches from the front faces of the trunnion slide assemblies. It will be found convenient to block the trunnion slide assembly to this height before assembling spring and plug to assure proper alinement of parts and ease of assembly. Screwing in the plug checks the gun * * * for_ ward rear face of bracket (31) and the front of slide (25).
* * # ❖	$
[A. G. 062.11 (7-17-42).] (C 2. July 30, 1942.)
By ORDER OF THE SECRETARY OF WAR :
G. C. MARSHALL,
Chief of Staff , Official :
J. A. ULIO,
Major General,
The Adjutant General.
476114°—42
O. S. GOVERNMENT PRINTING OFFICE: l»4t
TM 9-226
TECHNICAL MANUAL No. &-226
WAR DEPARTMENT, Washington, December 10, 19^0.
BROWNING MACHINE GUN, CALIBER .50, M2, WATER-COOLED, AND MOUNTS
Prepared under direction of the Chief of Ordnance
Section I. General.	Paragraph
Purpose----------------------------------------- 1
Scope------------------------------------------- 2
References-------------------------------------- 3
Data____________________________________________ 4
Description of machine gun______________________ 5
Operation of machine gun------------------------ 6
Description of antiaircraft machine-gun mount, , caliber .50, M2_________________________________ 7
Description of antiaircraft machine-gun tripod mount, All_____________________________________ 8
II.	Disassembly, assembly, and head space.
General_________________________________________ 9
Removal of groups from gun______________________ 10
Replacing groups in gun------------------------- 11
Head space______________________________________ 12
Disassembling___________________________________ 13
Assembling______________________________________ 14
Packing barrel__________________________________ 15
Changing barrels________________________________ 16
III.	Dismounting and mounting.
Dismounting antiaircraft machine-gun mount, caliber .50, M2_______________________________ 17
Mounting antiaircraft machine-gun mount, caliber .50, M2___________________________________ 18
Dismounting antiaircraft machine-gun tripod mount, All____________________________________ 19
Mounting antiaircraft machine-gun tripod mount, Ml_____________________________________ 20
IV.	Stoppages and immediate action.
Stoppages______________________________________ 21
Immediate action_______________________________ 22
273864°—41---1
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ORDNANCE DEPARTAIENT
Section V. Care and preservation.
General_________________________________________ 23
Points to be observed before, during, and after firing____________________________________   24
Care and cleaning of gun________________________ 25
Method of filling oil buffer-------------------- 26
Precautions to be observed during cold weather. 27
Precautions to be observed during gas attack___ 28
VI.	Sighting and fire control equipment.
Control equipment set, automatic gun, antiaircraft, Ml___________________________________ 29
Finder, range, 1-meter base, M1916______________ 30
VII.	Ammunition.
General_________________________________________ 31
Nomenclature____________________________________ 32
Classification__________________________________ 33
Identification__________________________________ 34
Model___________________________________________ 35
Ammunition lot number___________________________ 36
Identification card_____________________________ 37
Grade___________________________________________ 38
Marking_________________________________________ 39
Care, preservation, and, handling_______________ 40
Storage_________________________________________ 41
Authorized rounds_______________________________ 42
Data____________________________________________ 43
Precautions in firing blank ammunition---------- 44
Defects found after firing______________________ 45
Field reports of accidents______________________ 46
VIII.	Spare parts and accessories.
Spare parts_____________________________________ 47
Accessories_____________________________________ 48
Page
Appendix. List of references___________________________________ 87
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TM 9-226
BROWNING MACHINE GUN, CAL. .5 0, M2, WATER-COOLED 1-4
Section I
GENERAL
Paragraph
Purpose_____________________________________________________________________ 1
Scope----------------------------------------------------------------------- 2
References__________________________________________________________________ 3
Data________________________________________________________________________ 4
Description of machine gun-------------------------------------------------- 5
Operation of machine gun---------------------------------------------------- 6
Description of antiaircraft machine-gun	mount, caliber	.50,	M2-------------- 7
Description of antiaircraft	machine-gun	tripod	mount,	Ml------------------ 8
1.	Purpose.—This manual is published for the information and guidance of the using arms and services.
2.	Scope.—a. This manual contains all the essential information of a technical character required by the using arms for the identification, use, and care of the particular materiel described. In addition to describing the weapon and its mounts, it contains all the essential information required by the using arms to identify, use, and care for the ammunition, spare parts, and accessories, sighting and fire control equipment, and cleaning and preserving material.
&.	The disassembling outlined in this manual is the only disassembling which the using troops are authorized to perform.
3.	References.—All manuals to be used in conjunction with this manual are shown in the Appendix.
4.	Data.—a. Machine gun.
Weight of gun with water, 36-inch barrel-----------pounds.. 110. 00
Weight of gun with water, 45-inch barrel-------------do----121.	50
Weight of gun without water, 36-inch barrel----------do---- 94.	00
Weight of gun without water, 45-inch barrel----------do----100.	50
Weight of barrel assembly, 36-inch barrel------------do---- 14.	50
Weight of barrel assembly, 45-inch barrel------------do---- 17.	08
Over-all length of gun, 36-inch barrel-------------inches._ 57. 00
Over-all length of gun, 45-inch barrel-------------do------ 65. 93
Number of grooves in barrel-------------------------------- 8
Rate of automatic fire______________________shots/minute.. 500-650
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ORDNANCE DEPARTMENT
b.	Antiaircraft machine-gun mount, caliber .50, M2.
Tripod Pedestal type type
Weight of mount, complete-------------------pounds— 39*1. 50 323. 50
Weight of pedestal--------------------------do----- 94. 00	94.	00
Weight of tripod legs,	each----------------do—_	40. 00	-----
Weight of pedestal base---------------------do----- ------ 52.	00
Weight of cradle with	pintle--------------do-----113. 25	113.	25
Tripod spread, front to rear----------------inches— 77.00	------
Tripod spread, right to left----------------do----- 90.	00	-----
Height from ground to center line of gun----do----- 49.	00	49. 00
Elevation, maximum--------------------------degrees— 68. 75	68. 75
Depression, maximum-------------------------do----- 15.	00	15. 00
Traverse____________________________________do_____ 360.00 360.00
c.	Antiaircraft machine-gun tripod mount, Ml.
Weight of mount, complete--------------------------pounds— 284. 00
Weight of tripod group-----------------------------do-------191. 00
Weight of yoke, cradle, and shoulder stock group---do------- 93. 00
Tripod spread, all directions----------------------inches— 84. 00
Height from ground to center	line of trunnions------do--- 65. 00
Elevation, maximum---------------------------------degrees— 80. 00
Depression, maximum----------------------------------do----- 10. 00
Traverse_____________________________________________do----- 360. 00
d.	Weight of ammunition chest and. ammunition.
Chest, ammunition, caliber .50, M2, empty----------pounds—	29
Chest, ammunition, caliber .50, M2, loaded-----------do---	89
200 links, caliber .50-------------------------------do-----	8
200 cartridges, caliber .50, Ml----------------------do---	52
5.	Description of machine gun.—a. General.—The Browning machine gun, caliber .50, M2, water-cooled, is a recoil operated, belt fed, water-cooled machine gun. The metallic link, disintegrating belt is used in all firing of the gun.
b.	For use with M2 mount.—For use with the M2 mount, guns of current manufacture are assembled with a flexible back plate assembly (D35272, fig. 1). This back plate assembly is identical with the back plate assembly described in c below except for the omission of the spade grips and the spade grip handle frame. Normally, the side plate trigger mechanism of the mount is used to fire the gun. Therefore, the flexible back plate serves as an additional means of firing the gun while the removal of the spade grips provides needed clearance. When guns
4
5
ORD. I074G
Figure 2.—Browning machine gun, caliber .50, M2, water-cooled, right side view.
RA FSD 1216
Figure 1.—Browning machine gun, caliber .50, M2, water-cooled (modified), right side view.
TM 9-226
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having spade grips are required for use on the M2 mount, the spade grips and handle frames should be removed and replaced with upper and lower filler pieces. If these filler pieces are not available, or time and/or facilities will not permit of the removal of the handle frame and the installation of the filler pieces, the handle frame should be cut off thereby removing these spade grips.
c.	For use with Ml mount.—Guns manufactured prior to current orders were intended for use on Ml mount, and when so mounted are fired through the back plate trigger. The spade grips are desirable but are not essential.
d.	Cooling system.—The cooling system for the water-cooled machine gun consists of a water jacket surrounding the barrel and a water chest with pump. The water jacket of guns with 36-inch barrels contains 8 quarts of water and the 45-inch barrel 10 quarts of water. The water chest contains approximately 8 gallons of water. Both the water jacket and the water chest should be kept full at all times. In an emergency the full water jacket of the gun will permit cooling for short duration. However, for prolonged fire the water chest should always be coupled to the gun, and the entire circulating system kept full of water. The water absorbs the heat generated in firing the gun and thus prevents the barrel from becoming overheated. The steam tube is located in the top of the water jacket and is free to slide on the front and rear steam tube supports. Each of these supports is provided with a hole, the rear one being covered by the steam tube when the gun is elevated and the front one when the gun is depressed, thus preventing the escape of water from the jacket. The opposite hole, which is uncovered by this movement, allows the water and any steam generated through prolonged firing to escape through the steam tube and the outlet leading to the water supply or the circulating unit where any steam is condensed.
e.	Feeding.—By properly repositioning some of the component parts, the gun may be fed from either the right or left hand feed. However, this gun when mounted on the tripod mounts must be assembled for left hand feed. A retracting slide is provided which is connected with the bolt by means of the retracting slide bolt stud. The retracting slide handle remains stationary and in a forward position while the gun is firing, thus eliminating all moving parts outside of the receiver.
/. Mounting.—For antiaircraft purposes two mounts may be used: the antiaircraft machine-gun mount, caliber .50, M2 and the antiaircraft machine-gun tripod mount, caliber .50, Ml. For detailed description of these mounts, see paragraphs 7 and 8.
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TM 9-226
BROWNING MACHINE GUN, CAL. .5 0, M2, WATER-COOLED 5-6
g. Sights.—The gun is equipped with the conventional machine-gun front and rear sights. (However, the M2 mount is equipped with sights which permit off-carriage control. For detailed description of this sight, see paragraph 7.)
(1) Front sight.—The front sight is the conventional blade type and is protected by the front sight cover.
(2) Combination rear sight.—The combination rear sight is the conventional leaf type sight. The sight is adjustable for windage. The drift is offset automatically by the construction of the rear sight leaf. The wind gage arc on the base is graduated in mils. The leaf is graduated in yards up to 3,200 yards for caliber .50, Ml ammunition with a muzzle velocity of 2,400 f/s. New leaf, now under manufacture, will be graduated for ammunition of 2,660 f/s muzzle velocity. Calibration of the sight leaf for ammunition of different muzzle velocities may be obtained by the use of the elevating screw which raises or lowers the slide 1 mil. By pressing in the half nut, instantaneous adjustment of the slide can be accomplished.
h. Recoil mechanism.—An oil buffer mechanism in the gun cushions the force of the recoiling part. The M2 mount includes a recoil mechanism of the spring type which absorbs the recoil of the gun and also a counterrecoil mechanism which absorbs the force of the recoil spring when the gun is returned to firing position. For further description of this recoil mechanism, see paragraph 7.
6. Operation of machine gun.—Operation as discussed herein is divided into two sections:
a. Manual operation.—Manual operation is that operation performed by the gunner.
(1) To load.—Loading may be considered to include two distinct operations; entering the loaded belt properly into the belt opening, and thereafter operating the mechanism of the gun until it is closed with the cartridge in the chamber and a cartridge in the feedway gripped by the extractor for extraction on the next recoil stroke. The double loop end of metallic link belt should always be inserted regardless of whether right or left hand feed is employed.
(&) The first of these operations may be performed with the cover either open or closed. In either case, enter the double loop end of the belt through the feed opening until the first cartridge is beyond the belt holding pawl. Close the cover, if open. Pull the bolt completely to the rear by means of the retracting slide and release it.
(6) The second operation consists of pulling the bolt once completely to the rear and then allowing it to spring forward. This opera
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tion must start with, the action fully closed and the extractor gripping the cartridge in the feedway.
(2) To unload.— {a} Lift cover, remove belt, retract bolt, and make visual inspection of feedway, T-slot, and chamber to make certain that gun is unloaded.
(Z>) Release bolt and lower cover.
(c) Press trigger or sear mechanism to relieve tension on firing pin spring.
S. Mechanical operation.—Mechanical operation is that operation which is automatically performed by the gun itself when fired. The following explanation of mechanical operation begins with the gun assumed to be loaded and ready to fire. This explanation covers the mechanical operation of the gun itself. When fired from the antiaircraft machine gun mount, caliber .50, M2, the recoil mechanism of the mount affects to a slight degree the mechanical operation described herein (see par. 7).
(1)	Side plate trigger action on -first shot.—When the side plate trigger slide is pulled to the rear the action of the side plate trigger cam forces the sear slide inward. This in turn forces the sear downward, releasing the sear notch from the shoulder of the firing pin. The firing pin spring forces the firing pin forward to fire the cartridge.
(2)	Back plate trigger action on first shot.—When the rear end of the trigger, which is pivoted in the center, is pressed down, its forward end pushes up the rear end of the trigger bar; the trigger bar being pivoted in the center acts as a lever and causes the front end to press down upon the top of the sear, forcing the sear down and releasing the sear notch from the shoulder of the firing pin. The firing pin spring forces the firing pin forward to fire the cartridge.
(3)	Backward movement of recoiling parts.—The explosion of the cartridge forces the barrel to the rear, carrying with it the barrel extension and the bolt which is locked to the barrel extension by the breech lock. When the barrel has recoiled about % inch, the breech lock pin strikes the cam surfaces of the breech lock depressors. This unlocks the bolt from the barrel extension and permits the bolt to continue to the rear. As the barrel extension moves to the rear it strikes the accelerator and turns it backward.
(4)	Backward action of accelerator.—As the accelerator turns backward it strikes the bottom projection on the bolt and accelerates it to the rear. The shoulders on the barrel extension shank engage behind the claws of the accelerator, locking the barrel and barrel extension in a rearmost position to the oil buffer body.
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TM 9-226
BROWNING MACHINE GUN, CAL. .5 0, M2, AV ATER-COOLED	6
(5)	Backward movement of bolt.—As the bolt moves backward the driving spring is compressed. The bolt brings with it a cartridge from the belt gripped by the extractor and an empty case from the chamber gripped in the T-slot. The cam lug on the extractor rides along on top of the switch until near the end of the backward movement of the bolt. Then the extractor by action of the cover extractor cam is forced downward until its cam lug is below the switch.
(6)	Action of oil buffer.—As the barrel and barrel extension move backward together, the oil buffer spring is compressed, since the oil buffer piston rod is linked directly with the barrel extension by means of the hook on the shank projecting from the rear of the barrel extension and the hook on the forward end of the oil buffer piston rod; the oil buffer piston rod head and the oil buffer piston valve are driven rearward in the oil buffer tube forcing the oil through the restricted openings in both the piston rod head and valve. This supplements the action of the oil buffer spring in bringing the heavy recoiling parts tO' rest without damaging shock or strain on the gun. On the counterrecoil or forward movement of the barrel and barrel extension, the oil in front of the piston rod head will force back the piston valve, uncovering the openings and permitting the oil to pass readily from the forward to the rear side of the piston rod head and valve, thus permitting the rapid return of the parts to the firing position.
(7)	First action of feeding.—As the bolt moves backward, the stud on the belt feed lever riding in its cam groove in the top of the bolt moves the belt feed pawl laterally into position behind the next cartridge. The ammunition belt is prevented from falling out of the gun by the belt holding pawl.
(8)	Cocking action.—As the bolt moves backward, the upper end of the cocking lever is forced forward by the top plate bracket attached to the top plate, which brings the lower end of the cocking lever to the rear. When the lower end of the cocking lever moves to the rear it brings with it the firing pin, withdrawing the firing pin from the face of the bolt and compressing the firing pin spring against the sear stop pin. The shoulder of the firing pin engages in the notch in the sear under pressure of the sear spring.
(9)	Action of driving spring.—When the rear end of the bolt strikes the buffer plate, its remaining force is absorbed in the fiber buffer disks. The driving spring which has been compressed by the backward action of the bolt then forces the bolt forward. On guns manufactured after June 1940, two driving springs, one inside the other and wound in opposite directions, are used. By the use of two springs, greater initial spring load is provided which is an advantage in feeding ammunition
273864°—41---2
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during high angles of fire. The new assembly will be available for replacement of old type assemblies now in service.
(10)	Forward movement of bolt.—When the bolt starts forward the cam lug on the extractor riding under the switch rotates the extractor downward. This causes the extractor to force the cartridge down the T-slot in line with the chamber. The ejector knocks the empty case from the T-slot and holds the cartridge in line with the chamber. (The empty case may have already fallen out without the action of the ejector.) The upper end of the cocking lever is forced backward and the lower end moves forward away from the rear of the firing pin.
(11)	Release of recoiling parts.—The lug on the lower rear end of the bolt strikes the accelerator and rotates it forward. This unlocks the barrel extension from the oil buffer body. The barrel extension remains linked with the oil buffer piston rod. (See (6) above.) When the accelerator has been tripped the barrel extension and the barrel move forward, assisted by the oil buffer spring. Part of the forward force of the bolt acts through the accelerator to push the barrel extension forward.
(12)	Loading and locking action.—The extractor rises as its cam lug moves along the top of the extractor cam and the ejector moves outward, leaving the cartridge in the chamber engaged by the T-slot. The extractor grips the first round in the belt and is held down firmly, ready to extract it, by the cover extractor spring. The breech lock is forced upward by the breech lock cam and locks the breech just before the recoiling parts reach the firing position. (The breech lock engages in a recess cut in the bottom of the bolt and thus locks it firmly to the barrel extension and against the rear end of the barrel.)
(13)	Second action of feeding.—As the bolt goes forward, the stud on the end of the belt feed lever riding in its cam groove in the top of the bolt moves the belt feed slide and belt feed pawl in a lateral direction. The belt feed pawl carries the first cartridge against the cartridge stops, ready to be gripped by the extractor. The next cartridge is carried over the belt holding pawl, which rises behind it and holds it in position to be engaged by the belt feed pawl on its return movement.
(14)	Trigger action in automatic fire.—If the hand trigger is held down, the sear is disengaged just before the bolt has reached its forward position, thereby releasing the firing pin. The gun thus fires automatically, repeating the operation of functioning already described. (The release of the firing pin actually takes place when the recoiling parts are still about y8 inch from the forward position but after the breech is locked.) When the firing lever of the M2
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TM 9-226
BROWNING MACHINE GUN, CAL. .5 0, M2, WATER-COOLED 6-7
mount is depressed, the trigger control mechanism acts through the side plate trigger and the, sear slide in the bolt to disengage the sear from the firing pin, thereby igniting the cartridge. The reaction from firing causes the gun to recoil in the cradle. During counterrecoil the lug on the side plate trigger engages the mating lug of the trigger control, the sear is disengaged, and another cartridge is ignited. During this cycle the gun is fired semiautomatically.
Figure 3.—Antiaircraft machine-gun mount, caiber .50, M2, zero elevation.
7. Description of antiaircraft machine-gun mount, caliber .50, M2.—a. The antiaircraft machine-gun mount, caliber .50, M2 is normally assembled with tripod legs as shown in figures 3, 4, and 5. By removing the tripod legs and assembling a pedestal base the mount may be mounted on decks or other permanent positions. When assembled with tripod legs the mount is designated as antiaircraft machine-gun tripod mount, caliber .50, M2, and when assembled with pedestal base is designated as antiaircraft machine-gun pedestal mount, caliber .50, M2. Except for the pedestal base the pedestal mount is identical with the tripod mount described herein.
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b. The antiaircraft machine-gun tripod mount, caliber .50, M2 (fig. 5) consists principally of the pedestal (4), tripod legs (5), cradle (2), pintle (3), back rest (6), sight support (7), and the rear sight (8), and front right (26) assemblies. The lever of the trigger control mechanism is indicated at (27) and a safety lock at (29).
(1) Tripod (fig. 5).—The tripod is composed of the pedestal and the tripod legs.
Figure 4.—Antiaircraft machine-gun mount, caliber .50, M2, maximum elevation.
(tz) Pedestal.
1. The pedestal is a seamless steel tubing body lined with bronze bushing (9) (forced in place) which forms the seat for the cradle pintle. The lower portion of the pedestal is assembled with the pedestal base support ring (10) welded in place. The ring (10) is threaded to fit the removable hook (11) provided to hold down and stabilize the tripod on a hard base or in a truck. The pedestal is designed to be mounted on a pedestal
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TM 9-226
BROWNING MACHINE GUN, CAL. .5 0, M2, WATER-COOLED 7
base assembly in certain applications in which the tripod legs are not used, such as deck mounts for Army mine planters.
2. The base ring (12) welded to the pedestal body forms the connection of the pedestal with the tripod legs. The leg clamping ring (13) is threaded to fit the base ring and is used to lock the tripod legs in firing position. Tapered ring (14) of the clamping ring assembly engages a mating lug (21) on head (17) of each tripod leg, drawing the latter into place when the clamping ring is screwed down.
* K.
/	SIGHT, REAR
@ SIGHT, FRONT-—Lx/dtjU-f
— - ■	j	--® SUPPOET
T-F \	I X/'	,-@ LEVER
/ /	/ ।—®ee5t	/Uy
rrn	3 * * * 7
lljj________________"M
°	°"^°° -p ^~~>0» O Jeff '-----^-SAFETY LOCK
©GUN—J	N-@CRADLE
@ PINTLE-------©PEDESTAL
© BUSHING----------1 JEBRIVETy / ®WA5HEB
©PLUNGER-----------/	@NUT
©LEVER-------------/	©BOLT
R ©RING--------------< l	@P'N
®0NG-----------B \	" @NUT	©SPLINE-----
©RING----------Jcl 1	©WASHER	©FOOT-------
------® SPADE----------------
/ < V ©HEAD F '—— _____________________	—— \
,i C^tfgSP^jLEG-l ©HOOK J M©LUG	y.
L=J	PLATE-A (REVISION 3-1-39)
A.A.MACH.GUN MOUNT,CAL..50,M2
Figure 5.—Antiaircraft machine-gun mount, caliber .50, M2.
3. The pedestal lock assembly is composed of a spring actuated
plunger (15) which engages a mating groove in the pintle
and retains the latter in firing position. Cam lever (16)
withdraws the plunger when the lever is placed in hori-
zontal position, thereby permitting removal of the pintle from the pedestal.
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(5) Tripod legs.
1. The tripod legs are seamless steel tubing reinforced on the bottom, fitted on the upper end with head (17) and flattened on the lower end to assemble the spade (18), foot (19), and spline (20).
2. The bolt (22) is designed to fasten the tripod leg to the base ring. The body of the bolt is machined on both sides of the head to fit mating slots in the base ring. The ends of the slots are countersunk spherically to seat a spherical surface chamfer on the nuts (23). The taper pin (24) locks the bolt to the tripod head. Washers (25) with rivet (28) are provided to prevent the loss of the nuts. With the nuts engaged in their countersunk seats and the locking ring screwed down, the tripod legs are locked.
-
• /V ' *5	7 PLATE-D32826
L '"j
W K ‘	$ z •• ’’ ’
’ J" *	■ - (|)SLOT
RECOIL MECHANISM
s--REST- C 6 6195 \ K	80LT
■■■	® HANDLE
(js)skaft, long
1	flT''- SHAFT, SHORT	W
© Right side view.
Figure 6.—Antiaircraft
machine-gun mount, caliber .50, M2, cradle assembly.
(2) Cradle (fig. 6).— (a) The cradle is the basic design adopted for machine-gun mounts and is composed of right and left side plates, flanged and embossed to obtain maximum rigidity with minimum weight. The plates are assembled into a rigid unit and are kept in
14
TM 9-226
BROWNING MACHINE GUN, CAL. .5 0, M2, WATER-COOLED 7
| / ' "®’NUT
/	' I ' J
„ £	’ ' * "**’) The cradle pivots for movement of the gun in elevation and depression are controlled by the length of the cradle slots (3) on trunnion studs (4) mounted on the pintle, and are clamped to the pintle by bolt (5) with cradle clamping handle (6).
(c)	The machine gun is assembled to the cradle by the gun trunnions seated in the trunnion slide indicated at (7) and is locked in this position by the hinged caps (8) clamped by thumb nuts (9). The breech end of the gun is secured to the cradle by the rear gun joint pin (10) through the gun bracket and the slide of the recoil mechanism. If difficulty is experienced in lining up the gun bracket and the slide of the recoil mechanism to insert the joint pin, the joint pin should be inserted before the gun trunnions are seated in the trunnion slide. After the joint pin is inserted, the gun may be pulled forward against the action of the recoil spring and the trunnions pushed down into the recesses in the trunnion slide.
(d)	The back rest (11) is adjustable and clamped in position by cap screws (12). The sight support is bolted to the cradle by cap screws (13). The rear sight assembly is indicated at (16). The flexible cable connection for adjustment of the front sight in elevation is attached at (17) and for adjustment in azimuth at (18). The caps shown are provided for protection of the terminals when the cables are not in use.
(e)	The side plate trigger container is composed of body (19), cap (20), and chain (21), fastened to left side of the cradle. The cap has two pins 180° apart which mate with two slots in the open end of body (19). To remove the cap, press cap (20), turn counterclockwise, and pull apart. To assemble, reverse the above order.
(3)	Recoil mechanism, (fig. 7).—(a) The recoil mechanism is housed in frame (1) which is located between and secured to the cradle side plates. The rear gun joint pin passes through the gun bracket and slide (2) of the mechanism.
Note.—To aline the slide with the gun bracket, the spring actuated stop (3) with handle (4) and shaft (33) must be positioned to contact lug (5). After the first round is fired, the stop automatically returns to the disengaged position by the action of the torsion spring (6). Slight variations in spring adjustment may affect the location of the trunnion slide in such a way that the stop is not effective for the purpose of alining the gun slide with the hole in the bottom plate of the gun so that the joint pin may be inserted. If such is the case, the procedure outlined in (2) (c) above should be followed.
16
273864°—41----3
17
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"'M\’WrfVTAYVtV?VTAYoptftfrotypugB'tULHgj^tjy	*——•*.z>	pb \\
___ ______J	® HAKXE ' ORD. 13277
Figure 7.—Antiaircraft machine-gun mount, caliber .50, M2, recoil mechanism.
TM 9-226
7
ORDNANCE DEPARTMENT
(5) The lower recoil mechanism assembly is composed of bearing (7) secured to the frame by nuts (12) and machined to allow a slide fit for slide (2). The bearing houses the recoil spring (8) in addition to head (9), which mounts rod (10) provided to guide the component spring (11). The spring (11) compensates for the component weight of the machine gun between zero and maximum elevation.
(c) The recoil spring (8) is retained between the slide (2) and nut (13). The component spring (11) is seated between head (9) and threaded plug (15). The plug is provided for adjusting the tension of the spring and is locked by nut (16).
(<7) The two upper recoil springs (32) are assembled on shaft (14) to the rear of the slide (25) which carries the trunnion bearing. Front guide (26) is placed in front of spring (32) and the rear guide (27) at the rear of the spring (32).
Note.—These springs do not require any adjustment. The guides must be lubricated.
(4) Operation of recoil mechanism (fig. 7).—As the machine gun recoils, slide (2) moves with the gun to the rear, compressing springs (8), (11), and (32). The built-up spring pressure brings the gun to rest at the end of recoil and returns it to battery during counterrecoil. The counterrecoil of the gun is retarded by the counterrecoil springs (17). The firing mechanism is so arranged that the gun cannot be fired until it reaches a predetermined point in the path of counterrecoil, which is determined by the location of the lug which contacts the side plate trigger. Whether the gun is fired when it reaches this point or later depends on the relation of the moving parts of the gun mechanism, that is, the sear slide must be in position to be disengaged by the side plate trigger. The counterrecoil force of the gun is finally checked by the impulse of this shot. When firing a single shot and on the last shot, the counterrecoil spring absorbs the final energy of counterrecoil.
(5) Adjustment of recoil mechanism (fig. 7).— (a) The plug (28) should be 6T7K inches from the forward rear face of bracket (31) and lock nut (30) locked against it. Screwing in the plug checks the gun earlier in counterrecoil and will disturb the smoothness of firing if screwed in more than a few turns (clockwise). Unscrewing the plug (counterclockwise) reduces the counterrecoil spring load and aids smoothness of action. However, caution is necessary due to unavoidable variation in energy of cartridge, friction in links, pull, etc. The gun must not be allowed to come in battery, metal to metal with the forward rear face of bracket (31) and the front of slide (25).
18
TM 9-226
BROWNING MACHINE GUN, CAL. .5 0, M2, WATER-COOLED 7
(7) The constant recoil is obtained by the compensating spring which is acting on three planetary gears and racks. Gear (18) is secured to the cradle pintle and meshes into gear (20) which pivots on the cradle and meshes into rack (22).
(c) The mechanism is adjusted for normal recoil of the machine gun at zero elevation. As the gun is elevated, gears (20) rotate on gears (18) and pull racks (22) attached to head (9) forward. This movement compresses the compensating spring and maintains normal recoil.
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SET TRIGGER LEVER BRACKET
i=ca»
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ORD /3273
CRADLE TRUNNION
Figure 9.—Antiaircraft machine-gun mount, caliber .50, M2, trigger adjustments.
22
23
f~® SIGHT,FRONT
© BODY, READ SIGHT —-®	PIN
I E^Er	®XBCW	WF^® DISK
n u	/T
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Figube 10.—Antiaircraft machine-gun mount, caliber .50, M2, sight assemblies.
TM 9-226
7
ORDNANCE DEPARTAIENT
@ BOLT -—©PLATE
©BOO/.TPACK— irj \ Mx ®5L0T	@i^t—_7^7$%
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<7	ORD 13275
Figure 11.—Antiaircraft machine-gun mount, caliber .50, M2, front sight mechanism.
©
24
TM 9-226
BROWNING MACHINE GUN, CAL. .5 0, M2, WATER-COOLED 7
3.	Plate (8) is provided with elongated slots (10) on one end, with a countersunk seat on the other end to seat the heads of bolts (7).
4-	When removing the front sight mechanism, release knobs (9). This causes the spring actuated bolts to rise and release the plate. Push the plate in position so the body holes will permit raising the body off the bolts and out of the dovetail.
d. The front sight body (11) houses the front sight elevating screw (12) and moves in traverse on the front sight track body (3) on steel insert rollers (13). Traverse is by means of the ball bearing mounted traversing screw (14) driven by the flexible cable through a bevel gear drive (15). Index (32) travels along horizontal scale (20).
6. The front sight elevating screw (12) is mounted on ball bearings (16) and is raised and lowered by the internally threaded gear (17) driven by pinion (18) which in turn is driven by the flexible cable from the off-carriage station. The head of the elevating screw is flattened on both sides and machined with an undercut to seat the front sight. Attached to the elevating screw is an adjustable scale.
7. To assemble the sight to the elevating screw, place the sight with the flat at right angles to the flat on the screw head and turn the sight 90° in the undercut until the spring actuated plunger in the elevating screw head engages a mating detent in the sight.
Note.—Each graduation on the elevating scale and the traversing scale indicates a 1-niil change in elevation or traverse respectively of the machine gun.
c. When converting the tripod mount into a pedestal mount, the tripod legs are removed and the pedestal is mounted on the pedestal base. The pedestal base is located by the projection on the base fitting the mating recess on the pedestal base support ring and is secured to the pedestal by three eyebolts. The pedestal base is threaded left hand in three places. These three places contain sleeve nuts in which the eyebolts are assembled. These eyebolts fit into the lugs from which the tripod legs were removed. Bolts inserted through the lugs and eyes of the eyebolts complete the assembly. The pedestal is firmly secured to the pedestal base by turning the sleeve nut to tighten the eyebolts. The eyebolts should be tightened uniformly to assure accurate seating of the pedestal in the pedestal base.
273864°—41----4
25
TM 9-226
8
ORDNANCE DEPARTMENT
8. Description of antiaircraft machine-gun tripod mount, Ml (fig. 12).—The mount is of the tripod type in which the cradle and yoke are supported on a center support so that the gun can be freely moved by hand in azimuth through 360°. All positions of elevation are allowed from approximately 10° depression to 80° elevation.
Figure 12.—Antiaircraft machine-gun tripod mount, Ml.
A shoulder stock known as the shoulder stock, M2, is considered a part of the tripod mount and is provided for the purpose of assisting the gunner in steadying the gun in antiaircraft fire. When the locking handle is unscrewed a part turn, the adjusting bracket is free to slide on the center support, permitting the tripod legs and lower braces to be folded.
26
ORD 9184
TM 9-226
BROWNING MACHINE GUN, CAL. .50, M2, WATER-COOLED 9-11
Section II
DISASSEMBLY, ASSEMBLY, AND HEAD SPACE
Paragraph
General__________________________________________________________ 9
Removal of groups from gun_______________________________________ 10
Replacing groups in gun__________________________________________ 11
Head space______________________________________________________ 12
Disassembling____________________________________________________ 13
Assembling_______________________________________________________ 14
Packing barrel___________________________________________________ 15
Changing barrels_________________________________________________ 16
9.	General.—a. The following disassembling is the only disassembling authorized for using troops for the care, cleaning, and replacing of parts.
b. In removing springs caution should be exercised to avoid injury to personnel and damage to parts. When loosening parts which hold springs under tension keep personnel not directly engaged in the operation clear of the path the suddenly released spring might take.
10.	Removal of groups from gun.—a. Cover.—Release cover latch and open cover. The cover need not be removed as the other parts of the gun may be taken out without removing it.
Note.—Removal of the cover group is not recommended unless necessary for repair as it is difficult to reassemble due to the force required to compress the detent pawl spring.
b.	Back plate.—Release back plate latch lock and back plate latch and lift out back plate.
c.	Bolt group.—Press forward and away from the side plate on end of driving spring rod to release the retaining pin in head of rod from the hole in the side plate. Remove driving spring rod. Draw bolt to the rear until the bolt stud is in line with the hole in center of slot in the side plate. Remove bolt stud from bolt. Remove the bolt, complete, out of the rear end of the gun casing.
d.	Oil buffer.—Compress oil buffer body spring lock, using a cartridge point or a drift through the hole in the right hand side plate. Remove oil buffer, barrel extension, and barrel assembly by pulling out to the rear. Detach oil buffer assembly from barrel extension by pressing the accelerator forward.
11.	Replacing groups in gun.—a. Hold barrel and barrel extension in the left hand and oil buffer assembly in the right hand. With the index finger holding the accelerator up under the barrel extension shank, start the breech block depressors into the guideways in the barrel extension and press forward, allowing the shank of barrel
27
TM 9-226
11-12
ORDNANCE DEPARTMENT
extension to engage in the cross groove of the piston rod. Push forward as far as the oil buffer will go, having the accelerator back as far as possible. This will lock these components together so that the barrel, barrel extension, and oil buffer assembly may be placed in the casing of the gun as a unit. Push this unit forward in the casing until the lock of the oil buffer seats in the recess in the side plate.
b.	Press cocking lever forward in bolt and insert bolt into the casing. Push bolt forward until the hole for the bolt stud is in line with the enlarged opening in center of slot in the side plate. Insert bolt stud in bolt, being sure that the collar on the bolt stud is inside the side plate. Push bolt completely forward guiding the extractor from the front with the fingers to prevent it from catching.
c.	Insert driving spring rod assembly into the hole m bolt. Engage driving spring rod retaining pin in its seat in the right hand side plate.
d.	Replace back plate. When replacing the back plate make sure the latch lock is in the unlocked position until the back plate is latched.
e.	Close and latch cover.
12.	Head space.—The head space of a military weapon with a cartridge fully seated in the chamber is the distance between the base of the cartridge and the face of the bolt. In Browning machine guns, the head space is adjusted by obtaining the proper distance between the forward part of the bolt and the rear end of the barrel. The head space adjustment must be checked before firing.
a.	Head space adjustment.—(1) In the past the head space has been adjusted with the barrel, barrel extension, and bolt out of the gun. However, the best adjustment is obtained with the gun fully assembled. This method has the additional advantage of avoiding the loss of the cooling liquid.
(2)	To adjust the head space with the gun assembled, screw barrel into barrel extension, using the point of a cartridge until the action will just close without being forced. Then unscrew the barrel two notches.
Caution.—Care must be exercised to avoid roughening the barrel surface during adjustment. Care must also be exercised to eliminate binding of the barrel by the packing, or a false adjustment may otherwise be obtained.
b.	Effect of head space adjustment.—Probably the most important adjustment of the machine gun is the head space adjustment. Tests show that shot patterns are not adversely affected by the head space when the guns are adjusted as outlined above. In fact, better uniformity of shot patterns will be obtained when the guns are operated
28
TM 9-226
BROWNING MACHINE GUN, CAL. .5 0, M2, WATER-COOLED 12-13 with the above adjustment which is based on the fundamental design of the weapon. Tests have also proved that guns may be damaged and in some cases put out of action by using unapproved methods of adjusting the head space. Many reports show that difficulties with improperly guided belts and with firing mechanisms have been attributed to undue concern over head space adjustment.
(1) Insufficient head space.—When the head space adjustment is too tight, poor functioning will result as the breech lock will not fully enter its recess in the bolt. This condition may damage the barrel extension, bolt, or breech lock. Extraction trouble may also occur due to improper timing of locking and unlocking. Furthermore, with a tight head space adjustment the gun operates sluggishly because of the binding of the moving parts.
(2) Excessive head space.—If the head space is too great, a separation of the cartridge case may occur. Should there be any weakness in the base of the cartridge case, such as a split case, the possibility of a rupture is increased by excessive head space.
13.	Disassembling.—a. Bolt group (fig. 13).—(1) Remove bolt group from gun.
(2)	Remove extractor by rotating upward and pulling out from bolt. The ejector and ejector spring can be removed after driving out the ejector pin.
(3)	Lift bolt switch off bolt switch stud.
(4)	Rotate cocking lever fully backward and release firing pin by pushing down the sear. Remove cocking lever pin and cocking lever.
(5)	With thin end of cocking lever swing the sear stop out of its groove in the bolt into the center of slot in the bolt; then turn bolt over and push sear stop out of engagement with firing pin spring. Reverse bolt and remove sear stop from slot.
(6)	Depress sear and remove sear slide. Pull out sear and sear spring.
(7)	By holding the bolt with front end slightly elevated the firing pin extension and firing pin will drop out. The firing pin spring can be removed from the firing pin extension by driving out the firing pin spring stop pin. Take precautions to. prevent firing pin spring from flying out during the operation. This should not be done unless it is necessary to replace the firing pin spring.
(8)	The driving spring and driving spring rod collar can be removed from the driving spring rod assembly by driving out the driving spring rod collar stop pin from the driving spring rod. This should not be done unless it is necessary to replace the driving spring.
29
TM 9-226
13
ORDNANCE DEPARTMENT
r*HEAD~BI7l6B'	C0LLAR-A949Sn
' 'tIriwiiwimwiiJI PIN-A9788 LrOD-B6967 LSpRtN<* -35932	P1N-A9767^
^EXTRACTOR <4065
-^TUD-AI35a9
*-PIN-A9273	—	•
BOLT-026256
PIN-A936I-X
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J. /	^TUD-AI3424
-*SEAR-C4O67	LEVER-B9716^ ^STOP-BSTZS ^SWITCH-C4062
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^5LiDE-AI3595 ^EXTENSION-B 6946	^SPRING-A9353 ^^<17171
ORD. 8032
Figure 13.—Bolt group.
30
TM 9-226
BROWNING MACHINE GUN, CAL. .5 0, M2, WATER-COOLED 13
b.	Oil buffer group (fig. 14).— (1) Remove oil buffer, barrel extension, and barrel assembly from gun. Detach oil buffer from barrel extension by pressing accelerator forward.
(2)	Remove oil buffer body spring lock by pulling it to the rear.
(3)	Hold oil buffer body, bottom up, in the left hand with the index finger between depressors and prongs of accelerator. With the point of a cartridge press the stud on the end of the oil buffer tube lock spring to disengage it from its hole in the oil buffer tube body. At the same time raise accelerator upward and rotate to the rear. Remove oil buffer tube lock spring.
(4)	Drive out accelerator pin and remove accelerator.
(5)	The oil buffer tube assembly should not be disassembled unless absolutely necessary to replace the oil buffer spring. To disassemble, depress oil buffer spring guide sufficiently to clear oil buffer piston rod pin; turn oil buffer spring guide until oil buffer piston rod pin will pass through slots in the guide. Remove guide and spring. (See par. 72c(5), FM 4-135.)
Caution.—The oil buffer spring is under sufficient compression to cause injury to personnel.
c.	Barrel group.— (1) Remove barrel by unscrewing from barrel extension.
(2)	Remove barrel locking spring by sliding it forward out of its seat in barrel extension.
(3)	Push out breech lock pin and remove breech lock.
(4)	The barrel sleeve is permanently assembled to the barrel and should not be removed.
d.	Cover group (fig. 15).— (1) Remove cover pin cotter pin. Drive out cover pin and lift cover free from trunnion block.
(2)	Remove belt feed lever pivot stud cotter pin and pry belt feed lever off its stud, taking care while doing so that the belt feed lever plunger and spring do not fly out. In removing the belt feed lever see that toe of lever is in line with slot in cover, otherwise it will not pass out.
(3)	Remove belt feed lever plunger and belt feed lever plunger spring from belt feed lever.
(4)	Remove belt feed slide complete from its guides in cover.
(5)	Push out belt feed pawl pin which will enable the belt feed pawl, belt feed pawl spring, and belt feed pawl arm to be separated.
(6)	Remove cover latch spring by lifting its front end out of slot in cover and sliding it forward.
(7)	Remove cover extractor spring by releasing its rear end from its seat in the cover extractor cam and sliding to the rear.
31
TM
9-226
ORDNANCE DEPARTMENT
13
KEY-3 9739 7209-39630 5PRINO-39E99 P7N-39360	HE6D-S/7/69\Y3LYE-377/73
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KEY~ P 9330
•5PE/HG-/99393 YPL7E-3932& /	/	/	\	3
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LOCK-B8923	3PK/NG~B890e	GUiOE-B97/Sy
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ORD. 11686
Figure 14.—Barrel extension and oil buffer group.
32
TM 9-226
BROWNING MACHINE GUN, CAL. .5 0, Al2, WATER-COOLED 13
/	Ll£vE/2-C4057	/	t-SPPII\IG~89-74/
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ORD. 10758
Figure 15.—Cover group.
273864°—41----5
33
TM 9-226
13
ORDNANCE DEPARTMENT
(8)	Withdraw cotter pin from end of cover latch shaft and remove cover latch shaft assembly.
e.	Back plate group (figs. 16 and 17).—(1) Drive out back plate latch pin being careful that the back plate latch spring does not fly out upon removal of back plate latch.
(2)	Remove cotter pin, drive out latch lock pin, and remove latch lock and latch lock spring.
(3)	Drive out trigger pin being careful that the trigger spring does not fly out upon removal of trigger and trigger spacer.
(4)	Unscrew adjusting screw, remove adjusting screw plunger and adjusting screw plunger spring.
(5)	Remove buffer disks and buffer plate through the rear end of the buffer tube.
/. Casing group (figs. 18 and 19).— (1) To prevent injury to rear sight leaf, the rear sight movable base and rear sight leaf assembly should be removed from the rear sight fixed base. Turn rear sight windage screw knob until rack on movable base is entirely free from windage screw, then lift assembly from movable base pivot. Lift off movable base tension spring.
(2) To remove side plate trigger assembly from casing, withdraw cotter pin from side plate trigger bolt and unscrew side plate trigger nut. To disassemble—
(35^ LP/N-2II758I
lP!SJ-219275 l-5Pf?ING-/1935<3 I|t	W-HM	Wj
r-SPPING-PPJOO "* I W | PL8TE2/3535^ (T)	1-	-r- 7UBE-C4O<54-9 \	F
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/	PLUNGER$278	/
( ( . Pep-389-16
oro 10759
Figure 17.—Spade grip back plate for use on antiaircraft tripod mount, Ml.
36
TM 9-226
BROWNING MACHINE GUN, CAL. .5 0, M2, WATER-COOLED 13
XZV, //8M.-839G3 \3PPlNGy4P522 ^TP/PPER^/334/
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\ X	/	\	/ /	^PP/NO-03943
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PB/Er~PP387	^PMTE~P232G// R!VEF^/33P8 \
PLATE~P23257	RIVET-/49799 PRlCkET-8/28730
Figure 18.—Receiver group.
37
TM 9-226
13
ORDNANCE DEPARTMENT
EJUBE-C^OGB CBB/^~^I3B99-^3UPPOP^C30G9 SCPEWy4/35O! j ^3P/BG-A/3GGPy-Bl/SH/PG^/3Ga3\_^ LOCtf~A!3547 MJT-/U35O2 ' M	7
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ORO. 10755
Figure 19.—Barrel and water jacket group.
38
TM 9-226
BROWNING MACHINE GUN, CAL. .50, M2, WATER-COOLED 13
HTUBE-A/3695 /-FERRULE-A95I7 klEVER-B6969 v-DULT-AlD^oSt	\	/	\
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£SPRIN6-Ai3693
■ ................. . ... ...................
Figure 20.—
Retracting slide group.
39
TM 9-226
13-14
ORDNANCE DEPARTMENT
(4)	Lift end of trigger bar pin lock from its seat in the side plate, rotate downward about 90° and pull out trigger bar pin. Remove trigger bar.
(5)	Remove cotter pin from switch pivot nut. Unscrew nut and remove switch and switch spring.
(6)	Draw belt holding pawl pin out to the rear, taking care that the belt holding pawl spring does not fly out upon removal of the pawl. Remove belt holding pawl and spring.
(7)	Draw belt holding pawl pin, located on the opposite side of the feedway, out to the rear and remove link stripper and cartridge stops, front and rear.
(8)	Unscrew front barrel bearing lock screw jam nut and front barrel bearing lock screw. The muzzle gland, muzzle packing ring, and barrel packing may now be removed but it is not recommended unless necessary for repair or to repack the barrel. (See par. 15(7.)
Caution.—The front barrel bearing must not be removed except when necessary for replacement. If it becomes necessary to do this, the front barrel bearing lock must be removed before unscrewing the front barrel bearing.
(9)	The front end cap thread cover can be removed by unscrewing.
14. Assembling*.—a. Casing group.— (1) Replace front end cap thread cover.
(2)	If muzzle gland, muzzle gland packing ring, and barrel packing have been removed replace them and screw muzzle gland lightly against ring and packing as the gland will be adjusted and locked in place after the barrel is assembled to the gun. (See par. 15(7.)
(3)	Position link stripper and cartridge stops, front and rear, on right side of feedway and insert belt holding pawl pin.
(4)	Place belt holding pawl spring in its seat in left side of feedway. Position belt holding pawl over spring, compressing spring to allow insertion of belt holding pawl pin. Insert belt holding pawl pin.
(5)	Place switch and switch spring in position on left hand side plate. Screw on switch pivot nut and insert cotter pin.
(6)	Place trigger bar in its slot in top plate bracket so that hole in trigger bar is in line with hole in casing with long end of trigger bar to the front and the cammed surface down. Insert trigger bar pin with lock down and rotate lock into its seat in the side plate.
(7)	Replace retracting slide stud if it has been removed from retracting slide. Stake retracting slide stud to retracting slide. Replace retracting slide in retracting slide bracket with stud on the slide to the front. Position retracting slide lever spring in its seat in retracting slide lever with large loop of spring over the hole for the
40
TM 9-226
BROWNING MACHINE GUN, CAL. .5 0, M2, WATER-COOLED 14
retracting slide lever stud. Place retracting slide lever and spring on retracting slide stud with small loop of spring over retracting slide stop. Rotate retracting slide lever until it clears the stop. Depress lever making certain the large loop of retracting slide lever spring clears the collar of retracting slide lever stud. Replace retracting slide lever stud washer and nut. Replace cotter pin in retracting slide lever stud nut. Place retracting slide bracket bolt in its hole in retracting slide bracket. Screw on retracting slide bracket nut loosely.
(8)	Place retracting slide assembly on right side of casing with holes in the slide in line with holes in the side plate. Screw in retracting slide bracket screws and replace locking wires. Tighten retracting slide bracket nut and replace cotter pin.
(9)	Seat side plate trigger spring in the side plate trigger housing. Position side plate trigger cam over the spring and insert side plate trigger pin. Insert side plate trigger slide in its guides in side plate trigger housing and push the slide forward into position.
(10)	Place side plate trigger assembly on left side of casing, inserting the dovetailed end of housing into the forward slot in side plate. Adjust bolt to secure assembly to casing and tighten nut. Insert cotter pin in side plate trigger bolt.
(11)	Place movable base tension spring over stud on rear sight base. Place rear sight movable base and rear sight base assembly over stud in rear sight base. Engage windage screw with rack of movable base. Center sight by turning windage screw until sight index mark on movable base is in line with zero mark on windage scale.
b.	Back plate group.— (1) Insert buffer plate and buffer disks in buffer tube. Disks should be clean and free of rough edges and surfaces and should be assembled in the tube one at a time, being sure that each disk is firmly seated.
(2)	Replace adjusting screw plunger and spring in adjusting screw. Insert adjusting screw in buffer tube and tighten.
(3)	Replace trigger, trigger spacer, and trigger spring and insert trigger pin.
(4)	Replace latch lock spring and latch lock. Insert latch lock pin and cotter pin.
(5)	Replace back plate latch spring and back plate latch and insert back plate latch pin.
c.	Cover group.— (1) Insert cover latch shaft assembly in hole in cover and replace cotter pin.
(2)	Place forked end of cover extractor spring over stud in cover and engage the other end of spring in slot in cover extractor cam.
273864°—41---6
41
TM 9-226
14
ORDNANCE DEPARTMENT
(3)	Place cover latch spring over stud in cover and slide forward, making certain that the rear end rests on the cover latch.
(4)	Hold belt feed pawl with recess for belt feed pawl spring up and studs to the right. Place belt feed arm over studs on belt feed pawl with belt feed arm pointing to the right and holes in belt feed pawl and arm in alinement. Place belt feed pawl spring in its seat in pawl and position belt feed pawl in* belt feed slide. Insert belt feed pawl pin. Insert belt feed slide, complete, in its guides in the cover making certain that belt feed pawl arm is to the rear.
(5)	Place belt feed lever plunger and spring in rear hole of belt feed lever. Insert toe of belt feed lever through slot in cover and engaging belt feed slide. Position belt feed lever so that it goes over stud in cover, and at the same time compress belt feed lever plunger and spring so that they clear the side of the cover. Insert cotter pin in stud.
(6)	Place cover assembly on trunnion block and insert cover pin.
Insert cotter pin in cover pin.	j
d.	Barrel group.— (1) Insert breech lock in its guides in barrel extension making certain that bevel faces of breech lock are to the front with the double bevel on the top. Insert breech lock pin, taking care that both ends of pin are flush with sides of barrel extension.
(2)	Replace barrel locking spring by sliding it into its seat in barrel extension.
(3)	Screw barrel into barrel extension.
e.	Oil buffer group.— (1) Assembling.— («) If the oil buffer tube has been disassembled, place oil buffer spring over oil buffer piston rod. Position oil buffer spring guide so that slot in guide is in line with pin on oil buffer piston rod. Press down on oil buffer piston guide so that oil buffer piston rod pin passes through slot in guide and rotate guide until recesses in the guide are alined with the pin in the rod. Allow	i
pin to seat itself in recesses.
(7>) Insert oil buffer body spring lock in its groove in the body and	\
push forward.
(c) Position oil buffer tube lock spring over slot in oil buffer body with flanges of the spring over the enlarged cut in the slot. Depress spring into the cut and slide forward, raising stud end of spring up and over the end of oil buffer to seat stud in hole in oil buffer body.
() Method of connecting to machine gun.—The water chest and the machine-gun water jacket should first be filled with water. In filling the water chest, unscrew the filler cap but do not remove the filler cap strainer. Then proceed as follows:
1.	Remove the handhole cover from the pump compartment by taking out the eight screws.
2.	Remove the union caps from the outlet and inlet ports.
3.	Connect one hose from the outlet in the chest to the small hose connection bushing in the machine-gun water jacket.
78
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BROWNING MACHINE GUN, CAL. .5 0, M2, WATER-COOLED 48
/. Connect the other hose from the inlet in the chest to the large hose connection bushing in the machine-gun water jacket.
5. Replace the handhole cover, attach the crank, and place the chest so that the filler cap is at the top, as this is the only position in which the chest will function.
(c) Method of operation.—Turn the crank in a clockwise direction with a steady motion at the rate of approximately 35 revolutions per minute. This causes a steady stream of water to circulate through the water system. In order to make the most effective use of the water chest, the pump should be operated whenever bursts of 25 or more rounds are being fired, and continued without stop throughout the firing and thereafter until the temperature of the water in the machine gun is lowered to the temperature of water in the chest.
(tZ) Method of removing and replacing pump.
1. Remove the handhole cover from the pump compartment by taking out the eight screws.
%. Remove the union cap from pump outlet port.
3.	Loosen the hose clamp on the short rubber hose inside the compartment and slide the hose off the connection.
4-	Unscrew the three pump body screws which hold the pump in chest. In order to loosen one of the upper screws, the screw driver must be inserted through the hole in the large spur gear.
5.	Remove pump from chest. If pump is to be disassembled, it must be done by ordnance personnel.
6.	The pump is replaced in the chest in the reverse order to that in which removed.
Caution.—In replacing pump in chest, the three pump body screws should be screwed down gradually and evenly to avoid distortion of pump body and consequential misalinement of pump gear.
(e) Care and cleaning.
1.	The block strainer which is attached to the check valve should be cleaned occasionally. This is done by removing the filler cap and filler cap strainer, inserting the arm through the hole and rubbing the finger or a brush across the face of the strainer.
2.	When the water chest is not in service remove the filler cap and filler cap strainer, drain out the water, and thoroughly dry the interior by inserting the arm through the hole and wiping with waste or rags. Replace the filler cap strainer, filler cap, and the union caps of the inlet and outlet ports. Put the crank in the
79
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ORDNANCE DEPARTMENT
pump compartment and screw the handhole cover in place.
0	I
0	N.	1 .
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14249
Figure 32.—Chest, water, caliber .50, M3.
Note.—Chest, water, caliber .50, M3, recently adopted as standard, with a capacity of 8 gallons, will be issued when it becomes available.
(4)	Cup, filling.—The filling cup is used for filling the machine-gun water jacket. It consists of a conical shaped leather body having a small brass nozzle riveted to the bottom surface.
(5)	Machine,, link loading, caliber .50, M2.—The link loading machine (fig. 33) is used for rapid loading of ammunition into metallic links. It may be screwed to a bench, ammunition box, or other suitable support when in use, screw holes being provided in its base for this purpose. Links, properly assembled, are placed on the loading bed adjacent to the U-shaped stops, and cartridges are placed in the grooves provided. The loading is performed by the operation of the loading handle which, when pushed forward to the stop, will load the cartridges to the correct depth in the links. Care should be taken to handle properly that portion of the loaded belt that is adjacent to the section being loaded.
(6)	Oiler, filling, oil buffer.—This oiler consists of %-pint capacity oilcan with a nozzle 5 inches long. It is used only for filling the oil buffer.
(7)	Rod, cleaning, jointed.—This is a steel rod of five sections, the first two of which are permanently fastened together. The rear section is provided with a tubular steel handle which swivels on the rod. The first section has a slot formed for holding a cleaning patch and a threaded hole for attaching the cleaning brush.
80
TM 9-226
BROWNING MACHINE GUN, CAL. .5 0, M2, WATER-COOLED 48
P/H-A22S20, SCP[nA’232> CtrCN3K>H-BlJI300 PIH-A229I9 ,STOPA22924/SPA!NG-A22923 /HAMOLC-B131301
Figure 33.—Machine, link loading, caliber .50, M2.
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81
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ORDNANCE DEPARTMENT
(8)	Rod, cleaning.—This rod consists of two sections permanently fastened together. The rear section is provided with a tubular steel handle which swivels on the rod. The front section has a threaded hole for attaching the cleaning brush and a slot for holding a cleaning patch.
(9)	Wrench, adjusting packing ring.—This wrench which is used to turn the packing adjusting ring when adjusting the packing on the rear of the barrel is a single and spanner having its handle bent at an angle. At the end of the arc of the spanner a cylindrical lug is formed. When in use, this lug engages in one of the several holes formed in the packing adjusting ring.
(10)	Wrench, combination, M2 (fig. 34).—This is a special tool for disassembling, assembling, and making adjustments of the gun. Each opening and projection is marked to show its purpose.
(11)	Wrench, barrel holding.—This wrench is used to hold the barrel when using the packing ring adjusting wrench. It is made of flat steel, % inch thick, 7/16 inch wide, and 3 inches long. One end is shaped to adapt it to the serrations and general contour of the barrel.
c. Accessories for antiaircraft machine-gun mount, caliber, .50, M2.—(1) Bag, metallic belt link.—This canvas bag is secured to the chute of the mount to catch the ejected metallic cartridge links.
(2)	Chest, ammunition, caliber .50, M2 (fig. 6@).—The ammunition chest provides a convenient means of handling and feeding belted ammunition. The chest is attached to the mount by m'earis of slots on the sides of the chest. A removable crank is provided for use in loading the chest.
(a) General description.
1.	The chest is made of steel and provided with a hinge so that the upper half may be swung back for purposes of filling and cleaning. Latches are provided for locking the upper half in place.
2.	The upper half is provided with a spindle (reel) which is rotated by the removable crank, and a cartridge filler piece located around the spindle.
3.	The lower half is provided with rollers to facilitate feeding, and a stop to prevent the ammunition from dropping back when the tension is released.
(&)	Method of filling chest.
1.	Lock the cartridge filler piece in place over the projecting fins on the spindle by means of the set screw in the filler piece. The position of the filler piece is dependent upon whether left- or right-hand feed is contemplated.
82
TM 9-226
BROWNING MACHINE GUN, CAL. .5 0, M2, WATER-COOLED 48
STUD A-/34S7
.— --------------rf__H.,____________________________________t
L.	5 J01	10 Z 2__________________3
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END CAP	>---— tMOPEL SUPPORT
MUZZLE BEARING	MUZZLE GLAND
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, OIL BUFFER NUT _ 1	)	f	i
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Figure 34.—Wrench, combination, M2.
83
TM 9-226
48
ORDNANCE DEPARTMENT
2.	Pass the encl of the ammunition belt around the spindle in direction of arrow stenciled on side of chest so that the end of the belt is uppermost. Place ammunition belt over cartridge filler piece so that the fins on filler piece and spindle are between the first and second cartridges.
3.	Rotate the spindle in direction indicated by means of the crank. It may be necessary to hold the first layer of cartridges in place as the spindle is rotated.
J. Fill the spindle to approximately the height of upper half of chest. Pass the belt over hinge and down along back of lower half and along bottom of chest to the front. Then fill the lower half of chest in layers until the chest is filled to capacity (200 cartridges), and pass the first cartridge through the rollers.
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RECOIL MECHANISM WRENCHES, J" J?	«* —	..«s£. .	IT	!
SIGHTS&GEN.USE 3 —” "C. ~
ENGINEERS WRENCHES ' FLEXIBLE SHAFTS	SIGHT SOCKET
WRENCHES WRENCH
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■ I	^REWOR!VERS	REAR SIGHT OPEN
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STEEL CHEST, MS w/TRAY	I l( L	ft
STRAP WRENCHES	SIGHT CHEST	FRONT SIGHT
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PINTLE COVER
MJ '4^*	1	METALLIC LINK BAG
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AMMUNITION CHEST	C’*
CAL. 50,M2	TRIPOO SOCKET COVER
CRADLE ,TRIPOO & GUN COVER	RA PSD 1232
Figure 35.—Accessories for antiaircraft machine-gun mount, caliber .50, M2.
85
TM 9-226
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ORDNANCE DEPARTMENT
(Z>) The pin type spanner wrench is used in connection with adjusting various components of the front sight mechanism.
(c) The hook spanner wrench is used to adjust the locking nuts (12) of the recoil mechanism shown in figure 7.
(