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Japanese

Antitank “Lunge” Mine

WWII Japanese Antitank Suicide Lunge Mine

Japanese Antitank Suicide Lunge MineThis suicide mine, an antitank device used by Japanese Close-quarter Combat Units, consists of a conical-shaped hollow charge encased in a steel container, and a wooden handle. Three legs equally spaced around the base of the charge provide proper stand-off distance. A well in the apex of the charge contains the detonator.

The firing mechanism, quite simple in construction, consisting of a needle type striker, a shear pin, and a safety pin, is housed in a metal sleeve. This sleeve, which holds the mine” and the handle 2.4 inches apart, slips over the end of the handle and is held in place by the shear pin and safety pin; it is attached to the body of the mine by a threaded connecting ring.

To operate the mine, the soldier must first remove the safety pin, and then, using bayonet tactics, lunge forward striking the mine squarely against the tank. When the legs of the mine strike the target, the handle is driven forward breaking the shear pin, and the striker is driven into the detonator, initiating explosion of the mine.

Reports indicate that when head-on contact is made, the mine will penetrate 6 inches of steel plate; with contact at a 60° angle, steel plates of approximately 4 inches can be penetrated.

SPECIFICATIONS

Length of mine body (approx.)        12 ins.
Diameter of base of body (approx.) 8 ins.
Length of handle59 ins.
Diameter of handle1 1/4 ins.
Weight of explosive charge6 1/2 lbs.
Length of legs5 1/4 ins.
Weight of mine (total)14.3 lbs.

Japanese: p. 308.3 (May 1, 1945)

Categories
Japanese

High Explosive Rifle Grenade Model 3

High Explosive Rifle Grenade Model 3This grenade, designed to be fired from Models 38 and 99 rifles by means of a spigot launcher and wooden bullet, is similar in use and operation to the Model 91 rifle grenade. However, it is smaller and has a smooth-wall body rather than the serrated type. It contains a cyclonite primer enclosed in a brass container, a tetryl booster, and a three-ounce bursting charge of cast TNT; it is also fitted with an instantaneous fuze and a tail assembly with four fins spot welded to the rear part of the tube.

The grenade is armed by the removal of a safety fork. On impact, an inertia block is forced into the fuze body shearing a brass shear wire and driving the firing pin into the detonator.

SPECIFICATIONS

Diameter of grenade body         1.63 ins.
Length of grenade body 2.43 ins.
Wall thickness 1/8 in.
Overall length of grenade 7.88 ins.
Weight of grenade without explosive 14 ozs.
Weight of explosive body without explosive 10 ozs.
Length of fin assembly 4 15/16 ins.
Outside diameter of tube 1 13/16 ins.
Inside diameter of tube 1 1/16 ins.
Width of tail assembly 2 1/8 ins.
Length of tail fin 2 3/8 ins.
Width of tail fin 1/4 in.
Material of construction Steel
Weight of main charge 3 ozs.
Weight of primer 3 gr.
Weight of booster 1 gr.

Japanese: p. 304.2 (April 1, 1945)

Categories
Japanese

Pottery Hand Grenade

pottery-hand-grenadeThis hand grenade, made of terra cotta, and, like the Model 3 Flower Pot Land Mine, filled with Type 88 explosive, is assumed to be a Navy weapon. Except for the neck at the top, it is spherical, consisting of two halves baked together. It is light brown, in color, and lightly glazed both inside and out. The grenade is encased in a straw-colored, waterproof rubber sack.

The ignition system consists of a match composition and scratch block, a 4-5-second delay element, a lead azide initiator, and a tetryl booster. All are encased in a rubber tube except the match composition which is lacquered into the neck of the grenade. In order to operate the grenade, the small rubber covering is removed from the top and the scratch block is struck on the protruding match composition, igniting the delay element.

SPECIFICATIONS

Height (base to top of neck)         99 mm—3.9 ins.
Diameter 79 mm—3.1 ins.
Total weight 1 lb.
Weight of explosive 100 grams—3.5 ozs.
Pottery thickness 7/16 inch

Japanese: p. 304.2 (April 1, 1945)

Categories
Japanese

Conical Antitank Hollow Charge Hand Grenade

Japanese Conical Antitank Hollow-Charge Hand Grenade

This Japanese antitank grenade consists of a Pentalite (50/50 TNT & PETN) explosive charge cast around a thin aluminum cone, a wooden stand-off head, a fuze, and a tail attachment.

The explosive charge, which is shaped in the form of a hollow truncated cone, has a covering of thin waxed paper and a well in the upper end to receive the booster of the fuze. A cast ring pellet surrounds the cyclonite booster. The fuze, an all-ways impact type, is constructed in two parts which are threaded together. It will not function unless the mine has attained a velocity of approximately forty feet per second, and strikes a hard surface. The wooden base provides proper stand-off distance and has a central hole of slightly smaller diameter than that of the cone.

The grenade is encased in a silk bag, either white or olive drab in color, and closed by a draw-string at the bottom. A tail made of hemp is tied around the top of the grenade to provide stability in flight. The device, which will penetrate about 2 inches of armor plate, should be thrown from a distance of approximately ten meters.

A modified version of this grenade, referred to as the Type B, has been recovered. It differs from the grenade previously encountered in the Philippines in the following respects: it is smaller, the cover is yellow silk instead of canvas, the fuze is screwed into a metal seat on top of the mine, the fuze body is metal with a single-pronged safety pin, and the detonator tube is larger.

According to reports, there is also a larger grenade of the same type which has a Type 94 explosive charge.

SPECIFICATIONS

           Large Grenade          Small Grenade
Length of grenade 6 3/4 ins. 5 7/8 ins.
Length of tail 14 ins.  
Diameter at base 4 3/8 ins. 4 ins.
Length of fuze 1 7/8 ins. 1 7/8 ins.
Length of cone 3 3/4 ins. 2 3/8 ins.
Diameter of cone 2 3/8 ins. 2 ins.
Cone angle, apex 30° 38°
Weight complete 1.25 kg. .84 kg
Weight of grenade 1.14 kg. .76 kg.
Weight of fuze 42.3 grams 42.3 grams
Weight of explosive .87 kg. .60 kg
Weight of cone 141.7 grams 42.5 grams
Weight of base 56.7 grams 50.0 grams
Weight of booster 5.1 grams 5.1 grams

Japanese: p. 304.1 (April 1, 1945)

Categories
Japanese

20 mm Aircraft Cannon Type 99 Mk. II

20 mm Aircraft Cannon Type 99 Mk. II

This is a gun of higher power than the Type 99 Mk. I, 20 mm cannon. Like the earlier gun, it operates on the Oerlikon principle and is found both with drum type magazine feed (Mod. III—top photo) and with belt feed (Mod. IV—lower photo).

The principal differences between this model and the Mk. I consist of a longer barrel and a longer chamber. The barrel protrudes 18 inches beyond the leading edge when mounted in the wings of fighter aircraft. The projectiles used are identical to the Mark I, but the cartridge employed contains approximately 40% more propellant than the older type, thereby increasing the velocity of the Mk. II 500 to 700 foot seconds. The muzzle velocity of the weapon varies from 2,500 to 2,700 foot seconds depending upon the type of projectile used. The gun has been found in ZEKEs and HAMPs. It is probably fitted in RUFEs and as a flexible gun in the tail turret of BETTY.

SPECIFICATIONS

Caliber         20 mm (.787 in.)
Weight of gun 67 lbs.
Length of gun (overall) 73 ins.
Length of barrel 47 ins.
Length of rifling 41.5 ins.
Number of grooves 9
Depth of grooves 0.026 in.
Twist of rifling Right hand
Principle of operation Blow back
Feeding device French drum or belt
Capacity of drum 100 rds.
Cooling system Air
Sights Reflector type
Charging mechanism Pneumatic
Firing system Flexible cable
Effective range (est.) 600-700 yds.
Rate of fire (est.) 400-500 r.p.m.
Ammunition Ball, A.P., A.P./I., T., H.E., H.E./T., H.E./I.

Japanese: p. 254 (August 1, 1945)

Categories
Japanese

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.

SPECIFICATIONS

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.
Rifling
   Twist
   Form
   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)

Categories
Japanese

20 mm Aircraft Cannon Ho 5 (Browning Principle)

20 mm Aircraft Cannon Ho 5 (Browning Principle)

This weapon, an improvement on the 12.7 mm Japanese copy of the U.S. Cal. .50 aircraft machine gun, is a recoil-operated, disintegrating metallic link belt-fed, air-cooled, aircraft machine cannon. It is mounted as a fixed weapon and as such it is fired electrically by remote control.

The recoil mechanism consists of a metal cylinder into which is fitted a coil spring. Through the center of this extends a 5/16-inch rod which screws into a brass bushing. The rod extends through the spring follower which rests on the coil spring and is secured by two lock nuts. Buffering action takes place in the recoil direction only. There is no quick change barrel. Because of the weight of the bolt and the heavy recoil spring, a booster is used, this being found in the flash hider.

The gun has a high cyclic rate of fire, muzzle velocities of 2,304 f/s (A.P.), 2,430 f/s (H.E.), and a penetration performance of 7/8-inch homogenous plate at 20° at 200 yards; 1/2-inch at 20° at 580 yards. The maximum weight lifting capacity of the belt is 62 pounds.

The disassembly of the weapon is the same as the Browning Cal. .30 and Cal. .50 machine guns with a few minor exceptions. The Japanese weapon has no back plate latch. The back plate is held in place by two pins, one at the top, and one at the bottom.

SPECIFICATIONS

Caliber         20 mm (0.79 in.)
Weight w/accessories 104 11/16 lbs.
Weight w/o accessories 86 3/4 lbs.
Length (overall) 63 3/4 ins.
Sight radius
Principle of operation Recoil with muzzle cup
Feeding device Metal link belt type
Capacity of feeding device 100 rounds
Cooling system Air
Ammunition types A.P., H.E., Incendiary
Cyclic rate 950 r.p.m.
Type of sight Reflector
Weight of barrel 12 1/8 lbs.
Length of barrel 35.4 ins.
Length of rifling 31.5 ins.
Rifling
   Twist R.H.
   Form
   No. of grooves 8
   Depth of grooves
   Width of grooves
Chamber pressure
Muzzle velocity (A.P. Shot) 2,304 f/s
         (H.E. Shell) 2,430 f/s
Effective range 600 yds.

Japanese: p. 252 (June 1, 1945)

Categories
Japanese

20 mm Aircraft Automatic Cannon, Model 99 Mk 1 Flexible

20 mm Aircraft Automatic Cannon, Model 99 Mk 1 Flexible

This weapon is an air-cooled, blowback-operated, Oerlikon type machine cannon. It operates on the same basic principle as all Oerlikon cannons of this type. The Japanese gun is a close copy of the Swiss gun, in that it is designed for full automatic fire only. The gun is manufactured in Japan on Swiss machinery. The above illustration shows the flexible version.

A significant feature is that the parts which are subjected to little wear, such as the grips, mounts, gunners’ shoulder rest, and other exterior parts are generally made of light weight metal.

This weapon is almost identical with other Model 99 (1939), 20 mm aircraft cannon reported to be used in the majority of Japanese planes, both as fixed guns in fighter craft, and as flexible guns in bombing planes. The weapon is fed from a drum type magazine. It is cocked or charged by manual means, and has no semiautomatic charger or rounds counter. The cocking handle is rotated to draw the recoiling parts to the rear and cock the gun for the first shot, the gun firing from an open bolt. Cocking operations for succeeding shots are performed by the blowback operation of the gun itself.

SPECIFICATIONS

Caliber         20 mm—0.87 ins.
Weight (without magazine) 62 lbs.
Weight of 60 rd. magaine (empty) 20 lbs.
Length (overall) 55 ins.
Length of barrel 30 ins.
No. of grooves 9; Uniform right hand twist
Width of grooves
Depth of grooves 0.022 in.
Width of lands
Muzzle velocity (shell) 1,930 f/s.
Cyclic rate 510 r.p.m.
Traverse Flexible aircraft
Length of recoil
Turns of cocking handle required to cock piece 11 1/2 ins.
Ammunition HE; HE with tracer; HE with self-destroying tracer; HE-I; AP; AP tracer; AP-HEI; Long burning tracer; Practice
Wt. of HE projectile 4.50 ozs.
Type of feed 60 rd. drum

Japanese: p. 251 (June 1, 1945)

Categories
Japanese

7.7 mm Explosive Cartridge

Japanese Explosive Cartridge

This fixed round of ammunition consists of a brass cartridge case and a high explosive projectile. The semi-rimless case is tapered, forming a neck which fits over the projectile. The top of the neck is coned into the cannelure of the bullet. The base of the case is recessed to take a simple percussion type primer, and the rest of the case is filled with a propelling charge of graphited nitro-cellulose grains, about half of which, in the specimens examined, had a very fine axial perforation.

The brass projectile is cylindrical in shape with a truncated ogival nose. It contains a brass inner compartment, ogival in shape and open at the base, and a hammer consisting of a lead antimony plug encased in a brass sheath. The rear of the projectile is also open, the walls being turned in to retain the hammer. Both the main projectile and the inner compartment. are filled with the explosive charge, a mixture of PETN and RDX. A white felt washer pressed into the base of the inner compartment protects the explosive charge from the effect of setback when the round is fired.

When the projectile strikes a target, the hammer in the rear end sets forward crushing the explosive against the walls of both the inner and main compartments, causing the projectile to explode.

SPECIFICATIONS

Caliber        7.7 mm (.303 in.)
Weight of complete round 26.15 grms.—.915 oz.
Length of complete round 3 3/32 ins.
Length of cartridge case 2 9/32 ins.
Weight of cartridge case (without percussion cap) 14.93 grms.—.523 oz.
Weight of projectile 10.69 grms.—.374 oz.
Length of projectile 1 15/32 ins.
Maximum diameter 0.310 in.
Thickness of main compartment walls 0.021 in.
Weight of main compartment 2.95 grms.—.103 oz.
Thickness of inner compartment walls 0.008 in.
Weight of inner compartment 0.20 grms.—.007 oz.
Height of inner compartment 0.390 in.
Length of hammer 0.700 in.
Weight of hammer 6.65 grms.—.233 oz.
Diameter of hammer 0.258 in.

Japanese: p. 221 (April 1, 1945)

Categories
Japanese

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.

SPECIFICATIONS

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)