Tag Archive for 'machine gun'

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7.92 mm M.G. 15: Flexible Aircraft Machine Gun

7.92 mm M.G. 15: Flexible Aircraft Machine Gun

The M.G. 15, a reliable weapon, was the standard flexible aircraft machine gun in the German Air Force until it was replaced by the M.G. 81, because the latter is more easily manufactured. It is still used in some aircraft, however, and has been recently modified by the addition of a bipod and ground sights for use as a ground weapon for air force troops. Its efficiency as a ground gun is questionable because of the difficulty of changing barrels.

It is a recoil-operated, gas-assisted, drum-fed, air-cooled, automatic gun. The M.G. 15 has a Solothurn-type action, except that the locking arrangement is placed on the rear of the bolt instead of on the bolthead as in other German Solothurn-type guns. It was the first Nazi weapon to be fed by a saddle-type drum.

The Japanese have painstakingly copied it, even to the ammunition, and call their version the Model 98 (1938) 7.92 mm Aircraft Flexible Gun.


Caliber         7.92 mm (.312 in.)
Ammunition All 7.92 mm Mauser types
Weight 15 lb., 2 oz.
Feed Saddle-type drum (75-rd. capacity)
Rate of fire (cyclic) 1,000–1,100 rds./min.
Mount Flexible ball or ground bipod
Sights Aircraft ring and post or ground type.
Front—Blade. Rear—Adjustable open sight graduated 0-1200 meters (0-1308 yds.) in graduations of 200 meters.

German: p. 219

20 mm Aircraft Machine Gun (Modified Model 97 Antitank Gun)

20 mm Aircraft Machine Gun (Modified Model 97 Antitank Gun)

This Japanese 20 mm aircraft gun is a modified version of the Model 97 antitank gun described on page 101. It is a gas-operated, full-automatic, magazine-fed, air-cooled weapon. The barrel, of monobloc construction, is fitted with a muzzle brake and attached to the receiver by means of a bushing of the interrupted screw type. The magazine fits into a rectangular opening in the top of the receiver, and the empty cartridge cases are ejected from a similar opening in the bottom. The ejector is secured to the underside of the receiver top just behind the magazine opening.

The operation of the aircraft version of this gun is similar to that of the antitank rifle. The six phases are: loading, locking, firing, unlocking, extraction, and ejection.

The first three occur on the counterrecoil, and the last three on the recoil. The gun is cocked the first time by pulling the retracting handle to the rear. This retracts the operating group to the position where the sear will engage the gas piston and hold it to the rear. After the magazine is inserted and locked in place, the gun is ready to fire.

The gun was mounted in the dorsal turret of the Bomber “Helen” on a semicircular-shaped rack, and is fixed to the rack by the lower left hand edge of the receiver. The rack is used for elevating the gun. The gun and mount are in turn mounted on the turret ring. The sight used on this gun is a reflector type sight and it is believed that there is provision made for deflection shooting. A fixed version has also been reported. Documentary evidence discloses that the ammunition for the turret gun is referred to as HO1 and the fixed as HO3.


Caliber         20 mm (.79 in.)
Weight (without mount) 74 lbs.
Length (with muzzle brake) 68 7/8 ins.
(without muzzle brake) 67 1/4 ins.
Sight radius
Principle of operation Gas
Capacity of feeding device Magazine, 15 rds.
Inverted saddle type, 50 rds.
Cooling system Air
Ammunition types AP/T; HE/T; HE/I; Ball
Rate of fire (estimated) 300 rds. per min.
Type of sight Reflector
Weight of barrel
Length of barrel 47 ins.
Length of rifling (approx.) 42 ins.
   No. of lands & grooves 8
   Depth of grooves
   Width of grooves
Chamber pressure
Muzzle velocity (estimated) 2,500-2,900 ft. per sec.
Muzzle energy
Effective range 1,000 yds.
Type of mount Dorsal turret and fixed

Japanese: p. 253 (August 1, 1945)

Double Barrel Flexible Aircraft Machine Guns Model 100 and Model 1

Double Barrel Flexible Aircraft Machine Guns Model 100 and Model 1

These two weapons which are very similar offer the advantage of two guns being mounted in the space occupied by one gun of normal size, thus saving weight in the gun and mount, and space in the plane. A small ammunition supply making frequent magazine changes necessary is a disadvantage partially for the advantages of the double barrel principle.

The operating mechanism for both barrels is housed in a single receiver. This is a single forging, milled to house the two separate actions. The magazine opening is cut out of the top of the receiver, the ejection slot out of the bottom. Each action has its own back plate. The gas piston group resembles the Bren light machine gun in design. The bolt is a steel forging well machined. The gas cylinder tube is constructed of seamless steel tubing and is threaded to the receiver at the rear. The trigger assembly is made up of two separate sear assemblies riveted to the pistol grip framework. Two pistol grips are located about 6 inches apart; the sears are connected to a horizontal trigger bar mounting a trigger on either end. Both guns may be fired by depressing either trigger. The magazine is the saddle-drum type. Each side holds 50 rounds and feeds one gun. Each side has its own spring so that, in the event of a jam affecting one barrel, the other gun may continue to fire.

The Model 1 (1941) gun appears to be basically the same weapon as the earlier model, Model 100 (1940) which is shown at the bottom of the illustration. The Type 1 gun shown at the top of the picture has a head or shoulder rest attached to the gun. This rest is made of wood and canvas and is attached to the gun with steel frames. The specifications were secured from the earlier weapon.


Caliber         7.92 mm
Weight of gun 36 lbs.
Length (overall) 37.5 ins.
Length of receiver 16.25 ins.
Length of barrel 24.5 ins.
Length of rifling 22.37 ins.
Diameter of bore—
   across lands 0.310 in.
   across grooves 0.313 in.
Number of lands 4
Width of lands 0.0781 in.
Width of grooves 0.1718 in.
Depth of grooves 0.003 in.
Twist of rifling Uniform R.H.
Pitch of rifling 7° (approx.)
Type of operation Gas
Type of fire Automatic only
Type of feed Magazine, saddle-drum type
Capacity of magazine 100 rounds
Weight of magazine empty 7 3/4 lbs.
Weight of magazine filled 13 3/4 lbs.
Ammunition A.P.—Incendiary
Rate of fire (estimated) 400-600 r.p.m.
Range 250 to 350 meters

Japanese: p. 216.1 (March 1, 1945)

7.7 mm Heavy Machine Gun Model 01 (1941)

Japanese 7.7 mm Heavy Machine Gun Model 01 (1941)

This gun incorporates most of the features of the Model 92 Heavy Machine Gun, but is smaller and lighter. A total weight saving of 41 pounds in the gun and tripod mount is achieved. The barrel of the new gun is considerably shorter than that of the Model 92; therefore, the muzzle velocity is probably lower.

Both guns feed from 30-round strips, but the 01 (1941) uses rimless ammunition. The new gun incorporates the following modifications:

The barrel of the Model 01 may be quickly removed. The flash hider is screwed onto the muzzle, eliminating the knurled locking collar used on the older gun. The gas regulating system is similar to that of the 7.7 mm Model 99 (1939) Light Machine Gun. A smaller oil reservoir is used. A new method of attaching the ejection port cover allows easier access to the receiver which should aid in clearing stoppages. Minor changes in the metal sights have been made. A crank-shaped safety is fitted through the top of the sear housing with its handle at the left rear of the receiver. The new tripod is lighter and has different type spades. It also has a different mechanism for elevating the pintle support above the tripod base. The receiver of the Model 01 is lighter.


Weight (total)        69.9 lbs.
Weight (without mount) 34 lbs., 2 ozs.
Weight of mount 37 lbs.
Weight of tripod 36.3 lbs.
Length (overall w/flash hider) 42 3/8 ins.
Length (overall w/o flash hider) 38 ins.
Sight radius
Principle of operation Gas, full-automatic
Feeding device Metal strips
Capacity of feeding device 30 rounds
Cooling system
Ammunition types Model 92 ball, A.P. and tracer (rimless)
Rate of fire (estimated) 450-500 r.p.m. cyclic
200-250 r.p.m. effective
Type of sight Rear, calibrated from 100 to 2,200 meters.
Weight of barrel 11 lbs., 6 ozs.
Length of barrel 23 3/16 ins.
Length of rifling 22 ins.
   Twist R.H.
   No. of lands 8
   No. of grooves
   Depth of grooves
   Width of grooves
Muzzle velocity
Maximum range
Effective range
Type of mount Tripod
Traverse (total—on arc) 45°

Japanese: p. 214.2 (June 1, 1945)

30 mm Mk. 108 A-3: Aircraft Machine Gun

30 mm Mk. 108 A-3: Aircraft Machine Gun

The Mk. 108 A-3 is an automatic, air cooled, belt-fed weapon operated by blowback and firing electrically from an open bolt. Initial cocking and initial depression of the sear to release the bolt are accomplished by compressed air. The gun is mounted on its side, and fires through the propeller hub in ME 109 G fighters. It is attached at the forward end of the receiver to a blast tube which extends through the engine. This gun is unusual in being a blowback operated, low muzzle velocity weapon.

Sixty rounds of ammunition are fed by means of a disintegrating belt from an ammunition can mounted above the gun. On release of the sear, the bolt travels forward under the action of two driving springs. A projection on top of the bolt passes through the ring extracting a round and forcing it into the chamber. After firing the empty cartridge case reseats itself in its link. The ejection is accomplished by pawls actuated by camming grooves cut in the top of the bolt. Position of a new round takes place by the same action. A feature of the gun is the fact that the barrel and receiver do not move in recoil, the entire force of which is taken up by the rearward motion of the bolt against driving springs which act as buffers on recoil. There is no locking action between the barrel and bolt at any time.

All ammunition found to date has been high explosive, high explosive-tracer, incendiary and incendiary tracer. It is doubtful if the muzzle velocity is high enough for the effective use of armor piercing ammunition.


Caliber         29.6 mm (1.17 in.)
Weight (total) 265 lb.
Weight of gun 136 lb.
Weight of mount 28 lb.
Weight of ammunition can 36 lb.
Weight of ammunition (60 rounds) 65 lb.
Weight of recoiling parts 24 1/2 lb.
Length of gun with blast tube 7 ft. 6 3/4 ins.
Length of gun 3 ft. 5 1/4 ins.
Length of barrel 21 1/2 ins.
Number of lands and grooves 16
Maximum length of recoil of bolt 11 1/2 ins.
Rate of fire 500 rds./min.
Muzzle velocity (approx.) H.E.—1,650 f/s.*

*Not verified

German: p. 255

6.5 mm Heavy Machine Gun Model 3 (1914)

6.5 mm Heavy Machine Gun Model 3 (1914)

The Japanese 6.5 mm Model 3 Heavy Machine Gun, a gas-operated, air-cooled, full-automatic weapon with a comparatively low cyclic rate, although obsolescent, is being recovered in small quantities from battle areas. It is similar to the 7.7 mm Model 92, but is chambered for the 6.5 mm cartridge.

The gas piston and bolt assemblies, and the barrel and barrel sleeve may be interchanged in the two weapons. However, it is impossible to convert the Model 3 for use with the 7.7 mm ammunition as the strip feed port in the Model 3 is one-eighth of an inch narrower than that in the Model 92.

Various machining cuts found in the internal parts of the Model 3 were eliminated in the later model, to provide for ease of production. The oil reservoir is of slightly different shape and probably has a lower capacity than that of the Model 92. The trunnions are of two diameters. The part of the trunnion which contacts the trunnion bearing in the mount is of smaller diameter than that portion which extends beyond the mount. The head thus formed tends to reduce transverse motion.

The weapon has conventional spade grips provided with two finger triggers fixed integrally with the trigger lever so that either or both will fire the gun. There is no safety device.

Two rear sights are provided: one, a folding ring type anti-aircraft sight, is attached permanently to the rear top of the receiver; the other, a tangent curve, radius arm type, is offset to the right. The latter sight is graduated from 300 meters to 2,200 meters (328 yards to 2,406 yards). It is believed that a cartwheel typefront sight is used, as an adaptor for such a sight is riveted to the front of the cooling jacket.


Weight (w/ tripod)         122 lbs.
     (w/o tripod) 61.7 lbs.
Length 47.2 ins.
Sight radius 23.6 ins.
Principle of operation Gas
Feeding device Metal strips
Capacity of feeding device 30 rounds
Cooling system Air
Ammunition types Mod. 38, 6.5 mm ball ammunition
Rate of fire Cyclic — 450-500 r.p.m.
  Practical — 200 r.p.m.
Type of sight Two rear sights: folding ring, antiaircraft type; tangent curve, radius arm type, grad. 328-2,406 yds.
Weight of barrel
Length of barrel 29.2 ins.
Length of rifling 26.4 ins.
     Twist Uniform, R.H., one turn in 7.88 ins.
     Form Metford segmental
     No. of grooves 4
Depth of grooves
Width of grooves
Chamber pressure 58,800 lbs. per sq. in.
Muzzle velocity 2,434 ft. per sec.
Muzzle energy
Maximum range 4,376 yds.
Effective range 1,500 yds.
Type of mount Tripod
Elevation -15° to +90°
Traverse 33.5°

Japanese: p. 210.1

7.7 mm Lewis Machine Gun Model 92 (1932)

7.7 mm Lewis Machine Gun Model 92 (1932)

The Lewis type machine gun is used widely by the Japanese. Markings on a number of these guns found in the New Georgia area indicate that the weapon as used by the Japanese is of naval origin. It is also believed that the gun is used extensively for ship or air base protection as the tripod mount is adaptable for antiaircraft fire.

The Model 92 is of standard Lewis gas-operated, air-cooled, drum-fed design, equipped with a blade front sight and a rear peep-sight calibrated in hundreds of meters from 0 to 17. No allowance is made for windage or drift. Although no antiaircraft sight was discovered with the gun, a mount for such a sight is attached to the weapon.

The gun is mounted on a tripod having tubular steel legs which may be locked at various angles from the vertical. The tripod legs are attached to flat square plates which have holes in the center to accommodate bolts which are used to secure the tripod to the deck of a ship.

The head of the tripod has a 360° traverse. Without removing the gun from the mount, the main portion of the tripod head can be moved from a horizontal to a vertical position, and the gun attached to the top of the head for antiaircraft use. In this position, the limits of elevation are approximately -80° to +85°. Azimuth is calibrated in 2 mil intervals from 0 to 6,400 mils.

7.7 mm rimmed Navy ammunition fed from a 47-round drum is used. Ammunition chests recovered were found to hold 21 loaded drums.


Weight gun and tripod       122 lbs.
Length 39 ins.
Principle of operation Lewis gas-operated system
Feeding device Drum magazine
Capacity of feeding device 47 rounds
Cooling system Air
Ammunition types 7.7 mm full-rimmed ammunition
Rate of fire Cyclic-600 r.p.m.
Type of sight Blade front sight: rear peepsight calibrated from 0 to 1700 meters
Weight of gun 49 lbs.
Length of barrel 24 ins.
Length of rifling
     Twist Uniform, R.H.
     Form Concentric
     No. of grooves 4
     Depth of grooves
     Width of grooves
Chamber pressure
Muzzle velocity 2411 ft. per sec.
Muzzle energy
Maximum range 4000 yds.
Effective range 500 yds.
Type of mount Tripod
Ground mount -15° – +60°
Antiaircraft mount -80° – +85°
Traverse 360°

Japanese: p. 214.1 (June 1, 1945)