Biggerhammer
SIG AMT / 550
Stoner SR-25
Barrett .50
ANM2
HAC-7

Colt Light Aircraft Machine Gun
Rifle Caliber (MG 40-2)
(Air-cooled)

 

General Description

The Colt Light Aircraft Machine Gun M640-2 is an arm designed for airplane use and is capable of great rapidity of fire.

 

The gun is of a special light construction and can be fed with cartridges from the left-hand or the righthand side as may be desired, the change from one hand to the other being effected by a simple repositioning of some of the component parts taking very little time to carry out.

The gun is supplied in two types; the Flexible (or Observer) type is provided with a back plate having hand grips and a hand trigger, whereas the Fixed or Wing type is provided with a back plate without hand grips. There is a steel jacket which envelopes the barrel and to which, in case of the Flexible gun, sights are attached. At the front end of the barrel jacket is a muzzle attachment, a hole in the rear of which provides a bearing for the barrel.

The recoil buffer in both the Flexible gun and the Fixed or Wing gun is of the horizontal type.

The Flexible type gun is provided with a retracting slide which makes connection with the bolt by means of a stud in the side of the bolt.

The Fixed or Wing type gun is provided with an operating slide which makes connection with the bolt by means of a stud in the side of the bolt. Provision is made for attaching a cable so as to permit remote control. Incorporated in the operating slide is a feature whereby the slide when hand operated can be drawn back to its full extent and the bolt retained there by turning the slide handle to the right or left.

The cover is provided with a fitting at its front end which enables it to remain open in any one of three positions. This is useful when in flight if it should be desired to get access to the gun's mechanism in order to remove a faulty cartridge. The arrangement provided prevents the cover from being blown down upon the operator's hand and in order to close the cover, it is only necessary to exert a quick pull upon it.

Provision is made on the side plates of guns to receive a type of trigger motor to suit the mechanical synchronizing gear, thus enabling the Fixed type of gun to be fired through the plane of propeller rotation. The function of the synchronizing gear is to time properly the fire of the gun in relation to the position of the rotating propeller blades. The trigger motor may be mounted on right-hand side or left-hand side of gun as may be desired and to suit this adaptable feature the sear in the bolt mechanism of the gun can be assembled righthand or left-hand.

The guns are fed with cartridges loaded in metallic links.

The Colt Light Aircraft Machine Gun can be supplied to suit all standard military cartridges. The rate of fire, however, depends on the type of ammunition used.


Principle of Operation

The force of recoil is utilized to reload and fire the gun automatically as long as ammunition is supplied and the trigger is pressed.

Each time a cartridge is fired the recoil carries the barrel backward a short distance. This motion unlocks the bolt from the barrel extension and throws the bolt to the rear against the action of a spring. As the bolt goes back, it extracts the empty cartridge case from the chamber and at the same time draws a live cartidge from the links.

The driving spring then returns the bolt and barrel to the forward position, loads the cartridge into the barrel, ejects the empty cartridge case, locks the bolt to the barrel through the barrel extension and, if pressure is maintained upon the trigger, the cartridge is fired.

General Data, Weights, etc.
Flexible and Fixed or Wing Types

(Approximate)


Rate of fire . . . . . . . . . . . . . . . . About 1000 rounds per minute

..........................................................................................................Lbs.Ozs.
Flexible gun with sights and retracting slide.................................. 22 8
Fixed or Wing gun with operating slide...........................................21 4
Weight of 100 cartridges in links......................................................6 12
Weigh of barrel...................................................................................3 12
Weight of Metallic Link Filler............................................................8 ~13
Length of barrel.............................................................................. 23.9 inches
Length of gun (Flexible)..................................................................39.4 inches
Length of gun (Fixed).....................................................................39.4 inches

Regular equipment with each Flexible or Fixed or Wing Gun is as follows:

SPARE PARTS
1 Extractor complete consisting of:


1 Extractor
1 Extractor Plunger
1 Extractor Plunger Pin
1 Extractor Plunger Spring
1 Elector
1 Ejector Pill
1 Ejector Pin Spring
1 Ejector Spring


1 Sear complete consisting of:


1 Sear
1 Sear Spring
1 Sear Spring Plunger
1 Sear Spring Plunger Pin


1 Driving Spring
1 Firing Pin complete with Spring and Pin
1 Firing Pin Spring
1 Firing Pin Spring Pin
1 Ejector complete with Ejector Pin Spring
2 Ejector Pins
1 Sear Stop with. Pin complete
1 Cover Extractor Spring
1 Bolt Stud (to suite type of gun)
1 Belt Holding Pawl Pin complete
1 Belt Holding Pawl Spring
1 Belt Feed Lever Spring Plunger
1 Belt Feed Lever Spring
1 Belt Feed Pawl Spring
12 Cotter Pins (assorted sizes)

ACCESSORIES
1 Oil Can (filled)
1 Combination Punch
400 Metallic Links
1 Metallic Link Filler
1 Cleaning Rod
1 Drift
1 Ruptured Cartridge Extractor (to suit caliber)

1 Leather Case for Spare Parts and Accessories


Sights are provided with each Flexible Gun.
A Retracting Slide is provided with each Flexible Gun.
An Operating Slide is provided with each Fixed or Wing Gun.

SPECIAL NOTE:

In ordering, if it is desired to have the Flexible Gun complete with extra parts so that it can be instantly converted into a Fixed or Wing type of gun, the following parts will be necessary at extra cost :

Back Plate complete (of the type without grips)
Operating Slide complete
Bolt Stud

Similarly, if it is desired to have Fixed or Wing type gun complete with extra parts so that it can be instantly converted into a Flexible type of gun, the following parts will be necessary at extra cost :

Back Plate complete (of the double grip type) Trigger Bar with I'M and Spring
Retracting Slide complete
Retracting Slide Bolt Stud
Sights complete with bases.


Detailed Action


Starting with the gun loaded, when the trigger (271) is pressed the front end of the trigger bar (272) is caused to move upwards and acting upon the sear holder (245 1/2) raises it. The sear holder is in close contact with the sear (243 1/2) and a cam formed oil the sear riding in a notch in the sear holder causes the sear to move laterally thus releasing the firing pin (174) which flies forward under the action of the firing pin spring (175) and discharges the cartridge. At I he time of the explosion, the barrel (24) recoils to the rear carrying with it the barrel extension (23) and the bolt (51B) which is locked to the barrel extension by the breech lock (61). When the barrel and the barrel extension have recoiled about 3/8 of an inch the breech lock pill (64) strikes the slanting surfaces Of the lock frame tri projections causing the breech lock (61) to leave its recess in bolt and slide down the breech lock cam (62). At-full recoil of about 5/8 of an inch, complete unlocking of the bolt takes place.

The barrel extension (25) recoiling on to the back of the accelerator (1) forces it to the rear and the claw of the accelerator engaging with the shoulder in the bottom of the bolt (51B) separates it from the barrel (24) and throws it to the rear against the action of the driving spring (121).

As the bolt (51B) moves to the rear, the extractor (137) draws a cartridge from the links and as the extractor is forced down by the cover extractor cam (101), it forces the cartridge down into the groove oil the face of the bolt. At the same time the ejector (130C) pushes the empty cartridge case down out of the face of the bolt and it drops it from the gun. As the bolt (5113) moves to the rear, the firing pin (174) is cocked by tile action of the cocking

lever (85) riding in the top plate bracket (263) which is attached to the top plate (262). At the same time, the belt feed lever (151) riding in its cam groove in the top of the bolt, moves the belt feed pawl (161) lateral]y into position behind the next cartridge. While this action is taking place, the ammunition belt's prevented from failing back out of the gun by the belt holding pawl (43).

When the backward motion is completed, the driving spring (121) comes into play sending the bolt forward. The cartridge is held in the face of the bolt in the correct position to enter the chamber by means of the curved portion of the ejector (130C) which supports it underneath. After the cartridge has entered the chamber, the extractor plunger (142) riding in a groove in the extractor cam (138), raises the extractor (137) at the time the ejector reaches the clearance cut in the side of the barrel extension permitting it to swing out and leave the cartridge in the chamber as the extractor is raised.

As the bolt (51B) is nearing the end of its motion, it carries the barrel extension (25) forward and at the same time the breech lock (61) which moves forward with the barrel extension, is forced to ride up the breech lock cam and engage behind the shoulder n the bottom of the bolt, thereby locking the bolt to the barrel extension. If pressure is maintained upon the trigger the sear holder (245 1/2) is raised and sear disengaged as soon as the bolt has reached its forward position, thereby releasing the firing pin and causing the cycle of action above described to be repeated.


Manipulation

To Load: (Flexible Gun)

Without opening the cover, push the end of the loaded metallic belt through the feed opening as far as it will go, so that the first cartridge held by the belt holding pawl (43), prevents the belt from slipping back out of the gun. (Note: Insert bell so that the part of link marked "Colt" or caliber of gun is uppermost.) Pull the retracting slide handle (344) to the rear as far as possible and release it. Repeat this operation and the gun is loaded. Unless it is desired to fire immediately, the trigger safety (277) should be put on thereby locking the trigger (271).

To Fire:

Push the trigger safety (277) to left and press the trigger (271). Firing will continue as long as the trigger is pressed and there are cartridges in the belt.

To Unload:

Unlatch and lift up the cover (91). Lift the belt of cartridges out of the feed opening and close the cover. Pull the retracting slide handle (344) to the rear as far as it will go ejecting the cartridge which remains in the chamber. Point. the gun in a safe direction and snap the trigger to release the tension on the firing pin spring and also to make sure that the gun is unloaded.

Correction of Stoppage

If a stoppage occurs, pull the retracting slide handle to the rear as far as it will go and release it. This throws out the cartridge that was in the chamber and inserts another one. If on attempting to fire, this does not remedy the difficulty, lift up the cover and see if a battered or thick-headed cartridge is held in the face of the bolt. If so, remove it by pushing it upward with a screw-driver.

In case there is a ruptured cartridge in the chamber examine for reason and then, if necessary, re-adjust the headspace.

If the difficulty recurs and the cause is not apparent, examine the gun for broken parts.


General Instructions

Adjusting the Headspace or "Breeching the Gun":

"Breeching the Gun"
Note: Make sure that the barrel locking spring is in the disengaged position, described above, before attempting to unscrew the barrel.
There are no adjustments on this gun except the one for headspace termed "breeching". To adjust the headspace, take the bolt (51B) lock frame (192C193) barrel extension (25) and barrel (24) out of the gun. Detach the lock frame (192C-193, etc.). Raise the barrel locking spring (26) out of the notch in the barrel and slide it to the side where it can be held disengaged from the notch in the barrel. Then, having unscrewed the barrel about one turn and, while holding the barrel and barrel extension in a vertical position, muzzle end down, (See Plate 6) place the bolt in its guides in the barrel extension (after first having removed the extractor) allowing it to go right home against the inside face of the barrel extension. With finger, push the breech lock (61) as far as it will go into the recess in the bottom of the bolt and, while holding it, screw the barrel without using force into the barrel extension (25) until the face of the barrel stops against the front of the bolt, slacken off barrel from one to one and a half notches (this depending upon location of notch 'when barrel came to a stop) then allow barrel locking spring (26) to drop into the nearest notch of which there are fourteen in the barrel.

If, when the gun has been assembled, the position of the bolt stud indicates that the bolt does not go fully home remove the barrel with barrel extension from the gun again and after raising barrel locking spring out of notch in barrel and sliding to side unscrew the barrel in the extension one notch at a time until it is seen by trial that the bolt breeches. Replace barrel locking spring in barrel notch.


To Strip the Gun:

(Flexible and Fixed or Wing Types)

Open the cover then move latch lock (9) to right so that back plate latch (14) can be released. Slide back plate upwards and out of the gun. Press in and away from side plate on the end of the driving spring rod (122) to release driving spring rod head (123) from slot in the right side plate (253). Draw the retracting slide handle (344) in the Flexible gun or operating slide handle in the Fixed or Wing gun to the rear until the bolt stud is ]it line with the enlarged portion of slot in side plate then remove stud from bolt. Pull the bolt complete out of the rear end of the gun casing. Note: The assembled driving spring unit need not be removed from the bolt to do this. With the point of a cartridge or drift press in on the lock frame retainer (195) through the hole in the right side plate (253). Remove from the gun casing the lock frame (192C-193), together with the barrel extension (25) and barrel (24).

Grasping the barrel in the left hand and the lock frame in the right hand, press the accelerator (1) forward, thus separating the lock frame from the barrel extension. Place the barrel locking spring (26) in the disengaged position and unscrew the barrel from the barrel extension.

Remove the cover from the gun casing by removing cotter pin (98) and then the cover pin (97).

The gun has now been separated into the following groups: The gun casing; the cover, including the feed mechanism, the back plate with its assembled parts; the bolt with extractor; the lock frame with accelerator, etc.; the barrel extension; the barrel.

Note: This is as far as the gun should be stripped away from a base.

For further stripping, proceed as follows but this work should on1y be carried out in a workshop.

The Gun Casing: To Strip:

Remove cotter pin (95), cover detent pawl (94) and cover detent spring (96).

Pull out the belt holding pawl pins (44) after first removing retainer pin (38). Remove belt holding pawl (43) and spring (46) also front cartridge stop (80) and rear cartridge stop (81).

Do not remove the breech lock cam (62) but, if it must be removed, in re-assembling replace cotter pin (63) in nut (66) so that the cam (62) has the same small amount of play as before:

Remove mount adapter bolt nut cotter pins (206 and 206 1/4) and unscrew nuts (205 and 205 1/4). Remove bolts (204 and 204 1/4) and mount adapter, front (210).

Remove mount adapter screws (207) and remove mount adapter, rear (203).

Note: This is as far as the gun casing should be stripped.

To assemble, reverse the above procedure.


The Cover and Feed Mechanism: To Strip:

Remove belt feed lever pivot stud cotter pin (153) and, using the point of a cartridge, pry the belt feed lever (151) off its stud (152) taking care while doing so that the plunger (157) and belt feed lever spring (156) do not fly out.

Note: In removing the belt feed lever see that the toe of the lever is in line with the slot in the cover otherwise it will not pass out . Remove belt feed slide (17 1) complete from its guides in the cover (91). Remove plunger (157) and spring (156) from the belt feed lever (151).

To strip the belt feed slide (171 ) push out the belt feed pawl pin (164) which will enable the belt feed pawl (161) belt feed pawl spring (166) and belt feed pawl arm (162) to be separated. Do not remove the belt feed pawl arm pin (163) from the belt feed pawl (161). Push out cover latch spring stud cotter pin (115) and remove cover latch spring (113).

Remove cover extractor spring (104B).

Note: Do not strip the cover latch assembly (106, etc.).

To assemble, reverse the above procedure.

The Back Plate: (Flexible Gun) To Strip:

Remove trigger pin cotter pin (276) washer (50) trigger pin (275B) spring (10B) back plate latch lock (9) trigger (271).

Remove back plate latch pin (16) then remove back plate latch (14) latch spring (18) and plunger (19). Unscrew trigger safety bracket screw (279) then remove trigger safety spring (280) and trigger safety spring plunger (281). Remove trigger safety (277) and trigger safety bracket (278). Unscrew adjusting screw (6) with plunger (7) and spring (8) and remove buffer discs (70) and buffer plate (71).

To assemble, reverse the above procedure.

The adjusting screw (6) must at all times be tightly screwed down upon the buffer discs (70).

This requires attention from time to time.

The Back Plate: (Fixed and Wing Type Gun) To Strip:

Remove latch spring stop cotter pill (21) washer (50), spring (10B), stop pin (22 1/2) latch lock (9) and back plate latch spring stop (22).

Remove latch pill (16) and back plate latch (14), back plate latch spring plunger (19) and spring (18). Unscrew the adjusting screw (6) with plunger (7) and spring (8) and remove buffer discs (70), and buffer plate (71).

To assemble, reverse the above procedure.

The adjusting screw (6) must at all times be tightly screwed down upon the buffer discs (70).

This requires attention from time to time.

The Bolt: To Strip

Remove the driving spring assembly (121, etc.). Remove the extractor (137) by turning it to a vertical position and pulling it out.

Remove bolt switch (256) bolt switch plunger (257) and bolt switch plunger spring (258) from bolt.

Remove cocking lever pin (86) and cocking lever (85).

Using point of a cartridge or the cocking lever press in on the sear (243 1/2) which will cause firing pin (174) to snap forward. Using the cocking lever, swing the sear stop (247) out of its groove in bolt into center of bolt then push sear stop pin (248) from underneath with a drift and remove sear stop with pin.

Slide the sear holder (245 1/2) with its spring (249C) and plunger (250B) upwards out of the bolt. Remove sear (243 1/2) complete from bolt by sliding it laterally a short distance then lifting out.

Remove firing pin from bolt.

To assemble, reverse the operations.

Note: In assembling the sear (243 1/2) in bolt, if the bolt is to be employed in a Fixed or Wing Type gun, place the sear (243 1/2) in the bolt with the end carrying the sear spring. plunger and sear spring at the side next to the trigger-motor or solenoid.

The Extractor: To Strip:

With the point of a drift, push oil the end of the ejector pill (131) and remove pin together

with ejector (130C)) ejector pin spring (132) and ejector spring (133).

Caution: -- Use care to see that lite ejector and ejector spring do not fly out -while the eiector pin is being removed.

To assemble, reverse the operations.

Note: In replacing the ejector pin (131), see that the V notch is uppermost so as to engage with the ejector pin spring (132),

The Firing Pin: To Strip:

Using a drift, push out the firing pin spring pin (176) and remove the firing pin spring (175).

Note: Take precautions to prevent firing pin spring from flying out during tile operation.

To assemble., reverse the operations.

The Lock Frame: To Strip:

Push out accelerator pin (2-3) and remove accelerator (1).

With the aid of a drift, push out the lock frame retainer (195) and spring (196).

In the Flexible Gun push out trigger bar pin (273) arid remove trigger bar (272) and trigger bar spring (274). Remove barrel plunger (27) and barrel plunger spring (29) from the lock frame, precautions being taken to prevent the plunger and spring from flying out during the operation.

To assemble, reverse the operations.

The Barrel and Barrel Extension: To Strip:

Detach lock frame (192C-193 etc.) from the barrel extension (25). Unscrew the barrel (24) from the barrel extension after first having raised the barrel locking spring (26) out of the barrel notch and after it has been slid over into the disengaged position.

After barrel is separated from barrel extension, slide the barrel locking spring (26) out of extension. Push out the breech lock pin (64-65) and remove breech lock (61).

To assemble, reverse the operations.

Replace the breech lock (61) with bevel faces to front and double bevel on top.


Re-positioning of Parts

In order to change a gun feeding left-hand to feed right-hand or vice-versa, repositioning must be carried out in the following groups of parts:

I. The Feed Mechanism in the Cover
II. The Bolt and Extractor
III. Certain fittings in the gun casing

In order to change over a gun feeding left-hand to feed right-hand proceed as follows:

I. The Feed Mechanism in the Cover.

Open cover and proceed as indicated for stripping cover and feed mechanism. Remove the plunger (157) arid spring (156) from rear hole in the belt feed ]ever and place in front hole. With the belt feed pawl (161) stripped, as described under "The Cover and Feed Mechanism: To strip," place the belt feed pawl arm (162) in position on the pin (163) so that, in the assembled gun and with cover closed, the arm (162) will be to the rear. Then, after putting belt feed pawl spring (166) in its position, replace the feed pawl in the slide (171) and replace pin (164). Now put the belt feed slide (171) complete back into its grooves in the cover observing in doing so that it will feed "righthand." When the gap in the belt feed slide, for toe of the belt feed lever, (151) is in line with slot in the cover (91) replace the belt feed ]ever (151) using the point of a cartridge to aid in pushing the plunger (157) and spring (156) into position. Replace the belt feed ]ever pivot stud cotter pin (153). This completes the changes in the feed mechanism in the cover to afford right-hand feeding.

II. The Bolt and Extractor.

To change front left-hand to right-hand feeding.

Remove bolt complete from gun. Remove the extractor (137) and with the point of a drift push on the end of the ejector pin (131) and remove it. Note: Use care to see that ejector (130C) and ejector spring (133) do not fly out when doing this. Place ejector (130C) and spring (133) in position suitable for right-hand feeding (See Insert Diagram) arid replace the ejector pin (131) with the V notch uppermost.

To change the switch position:

With the extractor removed from the bolt, with forefinger and thumb raise the bolt switch (256) high enough to be clear of the bolt switch plunger (2,57) then give the switch a half turn when it will be seen that the other hole in the switch will come in line with the plunger (257). Push down switch and replace the extractor. This completes the changes in the bolt and extractor to afford right-hand feeding. I

III. The Fittings in the GunCasing.

Remove retainer pins (38) and withdraw the belt holding pawl pins (44) from each side which will enable the front cartridge stop (80), rear cartridge stop (81) and belt holding pawl (43) and spring (46) to be taken out and their positions reversed to suit the opposite hand feeding.

Change operating slide from one side to the other in fixed or wing type gun. Change retracting slide from one side to the other in the flexible type gun.

Replace bolt complete in gun, insert bolt stud in lefthand side of the bolt. Replace driving spring.

This completes the repositioning of parts to enable the gun to be fed from the right-hand side.

Reverse procedure to change from right-hand feed to left-hand.

To Convert a Flexible Gun into a Fixed or Wing Gun:

1. Remove retracting slide.
2. Remove sights and sight bases from the gun.
3. Remove back plate of the Flexible type.
4. Remove bolt and retracting slide bolt stud.
5. Withdraw partially, lock frame, barrel extension and barrel from gun and remove trigger bar, trigger bar pin and trigger bar spring from the lock frame.
6. Replace lock frame. barrel extension and barrel in gun.
7. Replace the bolt 'with driving spring in gun, also bolt stud.
8. Attach operating slide.
9. Insert a back plate of Fixed or Wing type.

To Convert a Fixed or Wing Gun into a Flexible Gun:

1. Remove operating slide.
2. Remove back plate of the Fixed or Wing type.
3. Remove bolt and bolt stud.
4. Withdraw partially. lock frame, barrel extension and barrel from gun and place a trigger bar, trigger bar pin and trigger bar spring in position in the lock frame.
5. Replace lock frame, barrel extension and barrel in gun.
6. Replace the bolt with driving spring in gun, also the retracting slide bolt stud.
7. Attach retracting slide.
8. Insert a back plate of the Flexible type.
9. Attach sight bases and sights complete to the gun.


Care and Upkeep

1. Make certain that gun is unloaded after firing and also before proceeding with any examination, cleaning and so forth.
2. In order that the gun may be kept in good condition it should be thoroughly cleaned and oiled after firing.
3. Remove any accumulation of residuum which may have formed during firing. In this respect give attention to the inside of the barrel bearing and plug. Scrape off residuum from muzzle face of barrel and clean around barrel where it moves in the barrel bearing. Certain powders cause a greater amount of residue to form than others. This must be removed as it builds up rapidly and interferes with the gun's correct functioning.
4. Oil working parts of gun before firing. In cleaning, the barrel should be given special attention and the bore left oiled after cleaning.
5. If gun has been taken apart, in re-assembling and in placing the bolt back in the gun, be sure that cocking lever is pressed forward in bolt and accelerator is back in the lock frame which at the same time brings the barrel back into recoiled position. The bolt cannot be placed in gun with the barrel in forward position.
6. Try gun's action by pulling back on the bolt and note that bolt returns freely under the action of the driving spring. 7. See that gun is breeched correctly.
8. See that bore is clear before commencing firing.
9. Do not fire more than 50 rounds on the ground without cooling the barrel. 'When firing from an airplane, the current of air, developed by speed of the plane, acts as a cooling agency.
10. In the event of the face of the bolt receiving damage caused by burning around the firing pin hole (this results from using faulty ammunition having punctures, leaky primers and so forth), the recoil plate (241) can be replaced but this work must be done in a workshop.
11. The barrel jacket can be tightened up on the trunnion block, should it become loose from long service. To do this, remove lock screw (317), lock washer (318) and plate (316) then turn barrel jacket up tightly against trunnion block. Replace plate, lock washer and lock screw.
12. If gun appears to be losing speed after long service, it may result from weak driving spring (121). Examine and replace, if necessary.

Bolt Group Assembly


PART NO..........NAME OF PART

51B Bolt (Alternate Feed) including

145 Extractor Stop
241 Recoil Plate
(
The above parts constitute Bolt Assembly)

85 Cocking Lever
86 Cocking Lever Pin
130C Ejector
131 Ejector Pin
132 Ejector Pin Spring
133 Ejector Spring
137 Extractor
142 Extractor Plunger
143 Extractor Plunger Pin
144 B Extractor Plunger Spring
174 Firing Pin
175 Firing Pin Spring
176 Firing Pin Spring Pin
243H Sear
244 1/2 Sear Spring
245 1/2 Sear Holder
246 Sear Spring Plunger
247 Sear Stop
248 Sear Stop Pin..
249C Sear Holder Spring
250B Sear Holder Spring Plunger
251 Sear Spring Plunger Pin
256 Bolt Switch
257 Bolt Switch Plunger
258 Bolt Switch Plunger Spring

 

SPECIAL NOTE REGARDING LUBRICATION


All guns which are to be fired in the air are to be lubricated with GARGOYLE TRANSFORMER OIL BB (U.S. Army Specn. 2-27D) or oil having similar characteristics.

Supplier: Socony Vacuum Oil Company of New York A supply of the above oil accompanies each aircraft machine gun shipped after January 15th, 1941.

THE FOLLOWING IS IMPORTANT


In a warm humid atmosphere the above oil offers no protection and metal surfaces coated with it will rust almost as rapidly as if there were no oil present.

Remove all heavy oil, grease, vaseline, etc., from guns before taking to the air.

Barrels should be protected in the usual way with sperm oil (U. S. Army Specn. 245A) after barrels have been thoroughly cleaned.


Component Parts

Prefix in front of part number indicates for which type the part is used.
Fixed and Wing type indicated by w, and Flexible indicated by *
Where no prefix given, part is used in both types.

PART NO......... NAME OF PART
1 Accelerator
2 Accelerator Pin
3 Accelerator Pin Spring
413 Accelerator Stop
6 Adjusting Screw
7 Adjusting Screw Plunger
8 Adjusting .Screw Plunger Spring
9 Back Plate Latch Lock
10B Back Plate Latch Lock Spring
11 Back Plate
13 Back Plate Cover
14 Back Plate Latch
16 Back Plate Latch Pin
18 Back Plate Latch Spring
19 Back Plate Latch Spring
Plunger
w2l Latch Spring Stop Cotter Pin
w22 Back Plate Latch Spring Stop
w22 1/2 Latch Spring Stop Pin
24 Barrel
25 Barrel Extension
26 Barrel Locking Spring
27 Barrel Plunger
28 Barrel Plunger Guide Pi n
29 Barrel Plunger Spring
30 Barrel Plunger Stud
31 Barrel Plunger Spring Stud
38 Belt Holding Pawl Retainer Pin (2)
39 Belt Holding Pawl Bracket Rivet (6)
40 Belt Holding Pawl Bracket (R. H.)
41 Belt Holding Pawl Bracket (L. H.)
43 Belt Holding Pawl
44 Belt Holding Pawl Pin (2)
46 Belt Holding Pawl Spring
47 Belt Holding Pawl Pin Head (2)
48 Belt Holding Pawl Pin Spring (2)
50 Washer (Back Plate Latch Lock)
51B Bolt (Alternate Feed)
53 Bolt Guilding Rib
54 Bolt Guiding Rib Rivet (2)
w56 Bolt Stud
59 Bottom Plate
60 Bottom Plate Rivet (16)
61 Breech Lock
62 Breech Lock Cain
63 Breech Lock Cam Cotter Pin
64 Breech Lock Pin
65 Breech Lock Pin Spring
66 Breech Lock Cam Nut
70 Buffer Disc (2 2)
71 Buffer Plate
74 Buffer Tube
75 Back Plate Pin
w76 Latch Spring Stop Support
77 Bunter Plate
80 Cartridge Stop (Front)ww
81 Cartridge Stop (Rear)
85 Cocking Lever

ww Consists of 3 parts in certain calibers.

86 Cocking Lever Pin
91 Cover
92 Cover Detent Bracket
93 Cover Detent Bracket Rivet (2)
94 Cover Detent Pawl
95 Cover Detent Pawl Cotter Pin
96 Cover Detent Pawl Spring
97 Cover Pin
98 Cover Pin Cotter Pin
101 Cover Extractor Cam
102 Cover Extractor Cam Rivet (Long)
103 Cover Extractor Cam Rivet (Short)
10413 Cover Extractor Spring
105 Cover Extractor Spring Stud
100 Cover Latch
109 Cover Latch Lever
110 Cover Latch Lever Pin
111 Cover Latch Pin
112 Cover Latch Shaft
113 Cover Latch Spring
114 Cover Latch Spring Stud
115 Cover Latch Spring Stud Cotter Pin
121 Driving Spring
122 Driving Spring Rod
123 Driving Spring Rod Head
124 Driving Spring Rod Head Pin
125 Driving Spring Rod Collar
126 Driving Spring Rod Collar Stop Pin
130C Ejector
131 Ejector Pin
132 Ejector Pin Spring
133 Ejector Spring
137 Extractor
138 Extractor Cain
139 Extractor Cam Rivet (2)
140 Extractor Feed Cam
141 Extractor Feed Cam Rivet (2)
142 Extractor Plunger
143 Extractor Plunger Pin
144 B Extractor Plunger Spring
145 Extractor Stop
w146 Back Plate Filler Piece, (Upper)
w147 Back Plate Filler Piece, (Lower)
148 Feedway Plate
w149 Filler Piece Rivet (4)
151 Belt Feed Lever
152 Belt Feed Lever Pivot Stud
153 Belt Feed Lever Pivot Stud
Cotter Pin
154 Belt Feed Lever Pivot Stud Pin
155 Belt Feed Lever Pivot Stud
Washer
156 Belt Feed Lever Spring
157 Belt Feed Lever Spring Plunger
161 Belt Feed Pawl
162 Belt Feed Pawl Arm
163 Belt Feed Pawl Arm Pin
164 Belt Feed Pawl Pin
165 Belt Feed Pawl Pin Spring
166 Belt Feed Pawl Spring

167 Belt Feed Pawl Spring Stud
171 licit Feed Slide
174 Firing Pin
175 Firing Pin Spring
176 Firing Pin Spring Pin
* 181 Handle Frame (Upper)
* 182 Handle Frame (Lower)
* 183 Handle Frame Rivet (4)
*184B Handle Grip (2)
* 185 Handle Grip Key (2)
*187 Handle Tube (2)
* 188 Handle Tube Screw (4)
w189 Latch Spring Stop Support Rivet (2)
192C Lock Frame (Right)
193 Lock Frame (Left)
194 Lock Frame Guide (2)
195 Lock Frame Retainer
196 Lock Frame Retainer Spring
197 Lock Frame Separator
198 Lock Frame Spacer
198 1/2 Lock Frame Rivet (2)
199 Lock Frame Rivet
203 Mount Adapter (Rear)
204 Mount Adapter Bolt, Small
204 1/4 Mount Adapter Bolt, Large
205 Mount Adapter Bolt Nut, Small
205 1/4 Mount Adapter Bolt Nut, Large
206 Mount Adapter Bolt Nut Cotter Pin
206 1/4 Mount Adapter Bolt Nut Cotter Pin
207 Mount Adapter, Rear, Screw (2)
210 Mount Adapter, Front
w216 Operating Slide Handle
w217 Operating Slide Tube Adapter
w218 Operating Slide Handle Stop
w219B Operating Slide Bracket (Front)
w220B Operating Slide Bracket (Rear)
w222D Operating Slide Hook Stop
w222 1/2 Operating Slide Hook Stop Nut
w223B 2 Operating Slide Rod I
w224B Operating Slide Rod Head
w224 1/2 ~ Operating Slide Rod Head Pin
w225B Operating Slide Hook
w225 1/2 Operating Slide Hook Pin
w226B Operating Slide Tube Collar
228 Operating Slide Mounting Block (Front) (2)
230 Operating Slide 'Mounting Block (Rear) (2)
231 Operating Slide Mounting Block Rivet (8)
w232B Operating Slide Spring
w233D Operating Slide Tube
w234B Operating Slide Bracket (Front)
w235 Operating Slide Bracket(Rear) (2)
w236B Operating Slide Assembly
w237 Operating Slide Handle Cotter Pin
w237 1/2 Operating Slide Bracket Screw Locking Wire (Front)
w237 1/4 Operating Slide Bracket Screw Locking Wire (Rear)
241 Recoil Plate (Bolt)
242 Rocker Shaft Bearing
243 Sear
244 1/2 Sear Spring
245~~ Sear Holder
246 Sear Spring Plunger
247 Sear Stop
248 Sear Stop Pin
249C Sear Holder Spring
250B Sear Holder Spring Plunger
251 Sear Spring Plunger Pin
2.53 Side Plate (R. H.)
254 Side Plate (L. H.)
256 Bolt Switch
257 Bolt Switch Plunger
258 Bolt Switch Plunger Spring
262 Top Plate
263 Top Plate Bracket
264 Top Plate Bracket Rivet (2)
265 Top Plate Rivet (12)
*271 Trigger
*272 Trigger liar
*273 Trigger liar Pin
*274 Trigger Bar Spring
*275B Trigger Pin *276 Trigger Pin Cotter Pin
*277 Trigger Safety
*278 Trigger Safety Bracket
*279 Trigger Safety Bracket Screw
*280 Trigger Safety Spring
*281 Trigger Safety Spring Plunger
*282 Trigger Support
*283 Trigger Support Rivet (2)
284 Trigger Motor Pad (2)
285 Trigger Motor Pad Rivet (12)
287 Trunnion Block
289 Trunnion Block Rivet (Oval Head) (10)
290 Trunnion Block Rivet (Flat Head) (6)
310 Barrel jacket
311 Barrel Jacket Adapter
312 Barrel Bearing. Front
313 Barrel Bearing Plug, Front k
314 Barrel Bearing Lock Washer, Front
3 15 Barrel Bearing Plug Lock Washer, Front
316 Locking Plate
317 Locking Plate Screw
318 Locking Plate Screw Lock Washer
319 Locking Spring Ring Screw (2)
*339 Retracting Slide Assembly
*340 Retracting Slide
*341 Retracting Slide Bolt Stud
*342 Retracting Slide Bracket
*343 Retracting Slide Bracket Screw (3)
*344 Retracting Slide Handle
*345 Retracting Slide Plunger
*346 Retracting Slide Plunger Spring
*347 Retracting Slide Plunger Stop Pin
*348 Retracting.Slide Bracket Screw Locking Wire (2)

The following Parts are supplied when Wind Vane Sights are ordered:

291 Wind Vane Sight Base, Front
295 Wind Vane Sight Clamp Screw (2)
296 Wind Vane Sight Clamp Screw Nut (2)
297 Wind Vane Sight Clamp Screw Cotter Pin (2)
298 Wind Vane Sight Socket Nut
331 Wind Vane Sight Base, Rear
3
35 Wind Vane Sight Clamp Screw (2)
336 Wind Vane Sight Clamp Screw Nut (2)
337 Wind Vane Sight Clamp Screw Cotter Pin (2)
338 Wind Vane Sight Socket Nut
350 Wind Vane Sight, (Front Assembly)
351 Wind Vane Sight, (Rear Assembly)

The following Parts are supplied when Post Type Sights are ordered:

372 Post Type Sight - Front Assembly Complete
373 Post Type Sight - Rear Assembly Complete
IMPORTANT. In ordering spare parts specify caliber of gun as well as "MG40-2," part number and name of part.

Accessories

82/83/84 Cleaning Rod
88 Combination Punch
90 Leather Case
214 Oil Can
215 Metallic Links
355 Ruptured Cartridge Extractor (to suit caliber)
356 Drift
420 Metallic Link Filler Base
421 Metallic Link Filler Slide
422 Metallic Link Filler Handle

Operating Slide - Type B

The operating slide makes connection with the bolt by means of a stud inserted in the side of the bolt. Incorporated in the operating slide is a feature whereby the slide when hand operated can be drawn back to its full extent and the bolt retained thereby turning the slide handle to the right or left, which causes the slide rod head to engage in a slot in the slide tube. The operating slide is secured to the side plate of the gun by means of brackets and three securing screws, the latter being prevented from turning by locking wires. The operating slide assembly can be attached to right hand or left hand side of gun as may be required.


Operating Slide Type B Component Parts

216 Operating Slide Handle
217 Operating Slide Tube Adapter
218 Operating Slide Handle Stop
219B Operating Slide Bracket, Front
220B Operating Slide Bracket, Rear
222D Operating Slide Hook Stop
222 1/2 Operating Slide Hook Stop Nut
223B Operating Slide Rod
224B Operating Slide Rod Head
224 1/2 Operating Slide Rod Head Pin
225B Operating Slide Hook
225 1/2 Operating Slide Hook Pin
226B Operating Slide Tube Collar
232B Operating Slide Spring
233D Operating Slide Tube
234B Operating Slide Bracket Screw,Front
235 Operating Slide Bracket Screw,Rear (2)
237 Operating Slide Handle Cotter Pin
237 1/2 Operating Slide Bracket Screw Locking Wire, Front
237 3/4 Operating Slide Bracket Screw Locking Wire, Rear

 

 


Note: Operating Slide Hook Pin (2Z5 1/2) is used only in the assembly when the Operating Slide Handle (216) is removed and Operating Slide is connected up to a remote control installation. In this assembly, it is necessary to dis-assemble the Operating Slide and Pass Pin (225 1/2 ) through hole "A " in Hook (225B) and Rod (223B) to prevent rod from turning. One Operating Slide Hook Pin (205 1/2) accompanies each Fixed Type Machine Gun (MG40-2) provided with Type B Operating Slide. When Type B Operating Slide is sent out separately, a n Operating Slide Hook Pin (225 1J) is also included for use if required. In a remote control installation, when it is desired to attach cable direct to hook (225B) the Rod Head (224B) should be assembled in the Tube (233D) with its projection downwards and engaging in the gap in the bottom of the Tube. The Rod (223B) will now remain stationary and in this case the Hook Pin (225112) is not employed.

Retracting Slide

The retracting slide makes connection with the bolt by means of a stud inserted in the side of the bolt. The retracting slide is carried in the retracting slide bracket which is attached to the side plate of the gun by means of three securing screws, the latter being prevented from turning 1)), means of locking wires. The retracting slide is provided with a handle which enables the slide to be drawn back when it is desired to charge the gun, unload the gun or relieve a stoppage. During the gun's functioning, the retracting slide remains stationary, being held in the forward position by a plunger and spring. The retracting slide assembly can be attached to the right hand or left hand side of gun as may be required.


Retracting, SlIde -- Component Parts

PART NO................ NAME OF PART
340 Retracting Slide
342 Retracting Slide Bracket
343 Retracting Slide Bracket Screw (3)
344 Retracting Slide Handle
345 Retracting Slide Plunger
346 Retracting Slide Plunger Spring
347 Retracting Slide Plunger Stop Pin
348 Retracting Slide Bracket Screw Locking Wire (2)

Last Modified on August 8, 1999
aalbert@biggerhammer.net