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Japanese 40mm Ho-301 Cannon

Photograph of Ho-301 cannon

Both photographs: U.S. Navy. Via Francillon (1979)

 
Cutaway Ho-301 40mm round

Specifications:

Ammunition
40 x 129 caseless HE
Projectile Weight     
1.29 lbs
585 g
Velocity 760 feet per second
232 meters per second
Range 490 feet
150 meters
Rate of fire     
450 rounds per minute
Gun weight
196 lbs
89 kg


The Ho-301 cannon was installed in a small number of Ki-44 "Tojo" fighters. It was a rather odd duck, achieving its high rate of fire by eliminating the cartridge and placing the propellant charge in a rear chamber of the projectile itself. This made for a simple and compact gun design, since there was no need for any cartridge extraction mechanism, but this came at the cost of a very low muzzle velocity, which adversely affected range and accuracy. One source (Mikesh 2004) has described the gun as an automatic grenade launcher and likened it to the Type 89 "knee mortar". The action was advanced primer ignition blowback. Ammunition came in boxes of 10 rounds, suggesting the fixed gun on the "Tojo" was good for one or two short bursts, though these would have been lethal against even the largest bombers if on target.

Photo Gallery


Gun and barrel

U.S. Navy

Cutaway of caseless round

U.S. Navy

References

Francillon (1979)

Mikesh (2004)

Williams and Gustin (2003)


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