Ho-301 cannon

Infobox Weapon
name=Ho-301 40 mm cannon


caption=A cutaway, showing the 40 mm caseless projectile.
origin=Japan
type=Aircraft Autocannon
is_ranged=yes
service=
used_by=Japan
wars=Second World War
designer=
design_date=
manufacturer=
unit_cost=
production_date=
number=
variants=
weight=49 kg (108 lb)
length=148 cm
part_length=78 cm
width=
height=
diameter=
cartridge=40 mm caseless
caliber=40 mm (1.57 in)
action=API blowback
rate=475 rounds/min
velocity=245 m/s (805 ft/s)
range=150 meters (490 ft)
max_range=
feed=10 round box
sights= The Ho-301 was a Japanese 40 millimeter calibre autocannon that saw limited use during World War II, on Japanese Army Nakajima Ki-44 and Kawasaki Ki-45 KAI aircraft. It was unusual in using caseless ammunition. Although the effective range of the cannon was only 150 meters (490 ft), the Ho-301 was light and rapid-firing for its caliber.

The caseless design revolved around a specially designed projectile, that was in effect a small rocket. The round used an internal propellent chamber at the rear of the projectile containing a ten gram silk bag filled with smokeless powder. Drilled into the base blade of the round are twelve 3.8 millimeter diameter exhaust holes. The propellent chamber is sealed by a thin aluminium sealing cup, which covers the exhaust holes. When the primer is struck, the bag of propellent ignites, and the pressure rises until the aluminium cup bursts, allowing the exhaust gas to rush through the exhaust holes pushing the projectile forward. The propellant was exhausted before the projectile left the barrel.

Because of the low muzzle velocity, the weapon was only suited to attacking bombers, and even here, the extremely low muzzle velocity made aiming difficult.

Ammunition specifications

* Length of projectile (fuzed): 129 mm
* Diameter of rotating band: 41 mm
* Diameter of body: 39 mm
* Wall thickness: 4 mm - 5 mm
* Weight: 0.590 kg
* Explosive content: 0.065 kg approx [TM gives content as 2 ounces of H.E. filling plus 0.1 ounces of primer and 0.2 ounce gaine.]
* Fuze: Direct acting impact fuze

See also

* MK 108 cannon

References

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