The main armament of Japanese medium tanks usually is the Model 94 (1934) 37-mm tank gun. It is a short-barreled, medium-velocity gun primarily designed for antipersonnel use. This factor, of course, was in keeping with the former Japanese policy of utilizing tanks mainly for infantry support. There is also a Model 98 (1938) 37-mm tank gun, thus far found mounted only in a Japanese fighter plane. It is a single shot with a semiautomatic sliding-wedge breechblock. The barrel is 49.5 inches long and the chamber is of the same size as the Model 94. This model, like the 94, is a medium-muzzle-velocity weapon. Replacement of low- or medium-muzzle-velocity guns by high-velocity weapons seems to be a reasonably certain trend in the modernization of Japanese armored vehicles.

There also are 47-mm and 57-mm tank guns installed in medium tanks but little is known about them. The 47-mm probably is a high-velocity antitank piece that has been modified for use as tank armament. It is likely that this weapon will be found with increasing frequency.

The Model 97 (1937) 57-mm tank gun has a tube 3 feet, 1.6 inches long. The gun has a vertical sliding breechblock actuated by a hand-operated lever which is counterbalanced by a breech-closing spring. There is no elevating mechanism but the gun is capable of a total traverse of 20 degrees without turning the turret. Two recoil cylinders of equal size are installed in the cradle.

 
MODEL 94 (1934) 37-MM TANK GUN

Characteristics
Caliber		37-mm (1.46 inch).
Muzzle velocity		2,100 feet per second (estimated).
Maximum elevation		+24°.
Maximum depression		-20°.
Traverse		10° right, 10° left, without rotating the turret.
Breech mechanism		Vertical sliding, semiautomatic in action.
Recoil system		Hydrospring.
Ammunition		APHE and HE.

 
MODEL 97 (1937) 7.7-MM TANK MACHINE GUN

Characteristics
Caliber		7.7-mm (0.303 inch).
Principle of operation		Gas operated, full automatic only.
Type of feed		Vertical box.
Magazine capacity		30 rounds.
Length of barrel		28 inches.
Overall length		46 inches.
Weight		34 pounds.
Cyclic rate of fire		500 rounds per minute.
Ammunition		Fires special Model 99 rimless.

 
MODEL 97 (1937) 57-MM TANK GUN

Characteristics
Caliber		57-mm (2.24 inches).
Weight		283 pounds.
Length of tube		3 feet 1.6 inches.
Length of chamber		5.1 inches.
Number of lands and grooves		20.
Maximum length of recoil		11 inches.
Maximum elevation		+45°.
Traverse		10° right, 10° left, without rotating the turret.
Type of breechblock		Vertical sliding.
Ammunition		Only high explosive rounds have been     recovered to date. They are characterized     by a rather short cartridge case.

 

Light Machine Gun

The light machine gun almost invariably installed in Japanese tanks is the Model 97 (1937) 7.7-mm machine gun. This weapon is gas operated and air cooled. It is a shoulder-controlled weapon with a specially designed stock and is fitted with conventional sights. When used for tank purposes, however, a telescopic sight of 1 1/2 power and 30-degree field of view usually is fitted. To prevent injury to the gunner, a heavy rubber eye-pad is attached to the rear of the telescope. The design is similar to that of Model 99 (1939) 7.7-mm light machine gun, an infantry weapon. The Model 91 (1931) 6.5-mm machine gun—actually the Model 11 (1922) 6.5-mm infantry weapon modified for tank use by removal of the bipod—also still may be encountered, although it probably is being replaced by the Model 97 (1937) 7.7-mm gun.