Imperial Japanese Army Ammunition - 40mm, 47mm, and 57mm Projectiles

Japanese Explosive Ordnance: Army and Navy Ammunition

 

We're starting to finish up on the remaining aircraft and tank projectiles.

40mm Ho-301 High Explosive Projectile

Dimensions
Length of projectile (Fuzed): 129mm
Length of projectile (w/o fuze): 108mm
Distance base to rotating band (lower edge): 15mm
Width of rotating band: 8mm
Diameter of rotating band: 41mm
Diameter of body: 39mm
Diameter of bourrelet: 39.5mm
Width of bourrelet: 6mm
Distance base to bourrelet (lower edge): 91mm
Wall thickness (propellant chamber): 5mm
Wall thickness (H.E. chamber): 4mm

Weights
Complete round (Fuzed): 1lb 4.7oz
H.E. charge: 2oz
Propellant: 0.4oz
Primer: 0.1oz
Fuze (with gaine): 2.1oz
Gaine: 0.2oz

Primer Dimensions
Length: 9mm
Diameter (Thread): 12mm
T.P.I. (Thread Per Inch): 34 L.H. (Left-Handed)

Used in: Ho-301 40mm aircraft cannon. This is an unusual weapon similar in design to an Oerlikon blow-back operated cannon, but with the head of the bolt machined as a piston which closes the breech at the forward end of its stroke.

Filling: The filling consists of TNT with a forward pellet of picric acid or TNT.

Propellant:
The propellant consists of small, greenish-gray, square flakes of smokeless powder (approx. 1mm square) enclosed in a silk bag which is inserted in the after cavity of the projectile. A sealing cup of thin aluminium fits around the after end of the propellant bag and the charge and cup are held in by a perforated base plate which screws (LH) into the base of the cavity. The base plate has an outer ring of twelve 3/16-inch holes and a central hole threaded (LH) to receive the small flush primer. The aluminium sealing cup is perforated by a single hole in the center to permit the flash from the primer to reach the propellant. The force of the propellant gases blows through the aluminium cup to open the main series of holes.

Fuze:
This is a simple direct-acting nose fuze with a central axial striker held in the unarmed condition by a slotted safety block which in turn is held by two spring-loaded detents.

Remarks:
There is also a practice projectile which has the same dimensions and appearance as the H.E. projectile. It is painted black overall and has a nose plug instead of a fuze.


Type 1 47mm High Explosive Projectile

Weight of complete round: 2.44kg
Weight of projectile (without fuze): 1.15kg
Weight of filling: 0.087kg

Filling: Two preformed paper-wrapped blocks taped together and waxed. The forward block consists of two pellets of picric acid, a ring pellet around the gaine and a solid pellet beneath the gaine. The after block is one piece of cast TNT.

Diameter at bourrelet: 47mm
Length of projectile (without fuze): 140mm
Length of propellant case: 283mm
Length of assembled round (without fuze): 389mm
Diameter of base of case: 72mm

Fuzing: Type 88 instantaneous nose fuze (gun type), Type 88 short-delay nose fuze (gun type).

Used in: Type 1 Anti-tank gun, Type 1 Tank gun.

Weight of propellant: 0.398kg
Propellant: Single perforated cylindrical grains (7/16-inch long, 5/32-inch diameter) of a graphited double-base powder of the following composition:
-Nitrocellulose: 60%
-Nitroglycerine: 34.5%
-Ethyl centralite: 3%
-Diphenyl formamide: 2.5%



Type 1 47mm Armor Piercing Projectile

Weight of complete round: 2.75kg
Weight of projectile (Fuzed): 1.38kg
Weight of projectile (w/o Fuze): 1.27kg
Weight of filling: 0.018kg
Filling: 90% RDX, 10% Paraffin
Diameter at bourrelet: 47mm
Length of projectile (w/o fuze): 143mm
Length of propellant case: 283mm
Length of assembled round: 398mm
Diameter of base of case: 72mm
Width of rotating band: 12mm

Fuzing: Small Mk 2 base fuze (Short delay)

Used in: Type 1 Anti-tank gun, Type 1 Tank gun

Tracer: Yellow, 5 grams
Weight of propellant: .0398kg
Propellant: Single perforated cylindrical grains (7/16-inch long, 5/32-inch diameter) of a graphited double-base powder of the following composition
-Nitrocellulose: 60%
-Nitroglycerine: 34.5%
-Ethyl centralite: 3%
-Diphenyl formamide: 2.5%


Type 90 5.7cm (57mm) High Explosive Projectile

Weight of complete round: 2.91kg
Weight of projectile, filled (Fuzed): 2.36kg
Weight of filling: 0.25kg
Filling: TNT
Diameter at bourrelet: 57mm
Length of projectile (w/o fuze): 181mm
Lenght of propellant case: 121mm
Length of assembled round (without fuze and adapter): 280mm
Width of rotating band: 9.5mm

Fuzing: Type 88 short delay fuze

Propellant: Mk 1 square grain - 113g

Used in: Type 90 Tank gun, Type 97 Tank gun



Type 90 5.7cm (57mm) Substitute projectile

Weight of complete round: 3.04kg
Weight of projectile, filled: 2.23kg
Weight of filling: 0.07kg
Filling: Black Powder
Diameter at bourrelet: 57mm
Length of projectile (w/o Fuze): 183mm
Length of propellant case: 121mm
Length of assembled round (w/o Fuze): 272mm
Width of rotating band: 9.5mm

Fuzing: Type 88 short delay fuze

Propellant: Mk 1 square grain - 113g

Used in: Type 90 Tank gun, Type 97 Tank gun

Remarks:
This projectile is made of cast iron and has very thick walls.



Type 92 5.7cm (57mm) Armor Piercing Projectile

Weight of complete round: 3.13kg
Weight of projectile, filled and fuzed: 2.58kg
Weight of filling: 0.1kg
Filling: Two sections of explosive, individually wrapped in paper
-Upper section: pressed picric acid and wax
-Lower section: Cast TNT
Diameter at bourrelet: 57mm
Length of projectile (w/o fuze adapter): 181mm
Length of propellant case: 121mm
Length of assembled round: 280mm
Width of rotating band: 10mm

Fuzing: Type 92 small base fuze

Propellant: Mk 1 square grain - 113g

Used in: Type 90 Tank gun, Type 97 Tank gun



57mm Ho-401 High Explosive Projectile

Weight of complete round: 2.15kg
Weight of projectile, filled and fuzed: 2.58kg 1.47kg
Weight of filling: No Data
Filling: No Data
Diameter at bourrelet: 57mm
Length of projectile (w/o fuze): 163mm
Length of propellant case: 121mm
Length of assembled round: 270mm
Width of rotating band: 11m

Fuzing: No Data

Propellant: No Data

Used in: Ho-401 aircraft cannon

Note: I believe there is an error with this entry, in my book. The complete round weighs less than the projectile (filled and fuze) which is impossible. In pounds, it gives the round at 4.75 and the projectile at 3.25. Using a mass converter, 3.25lb is the equivalent of 1.47kg.


Next time: 70mm Projectiles, including Hollow Charge types!