Monday, 18 May 2015

Imperial Japanese Army Ammunition - 12.7mm and 20mm Projectiles

Japanese Explosive Ordnance: Army and Navy Ammunition

We start to get into the higher munitions, starting with the 12.7mm cartridge.  It should be noted that the 12.7mm is similar to the .50 cal bullet, but the cartridges have different lengths, which is a very important detail as the diameter alone can be misleading.  The Japanese Army only had one machine gun chambered in 12.7mm, the Ho-103 or Type 1, and was used in aircraft.  The Ho-103 was sometimes referred to the Ho-104, and the only difference between the Ho-103 and Type 1 was that the former was used in a fixed position in the wings and the latter was used in a flexible position as a defensive gun on a bomber.

12.7x81mm Aircraft Cannon Ammunition
Once again, it's a bit of a misnomer to call the 12.7mm round a cannon round, when examples like the MG131 13mm Machine Gun and the M2 Browning were not called cannons.  In any case, the Ho-103 saw extensive use in the air force.

7 variants exist for it, although 3 differ only slightly.

Ball: CuNi jacket and Lead core
A.P.T.: Brass jacket with Steel core
H.E.I. (fuzed Japanese): Brass jacket and P.E.T.N. incendiary and steel core
H.E.I. (fuzed Italian): Brass jacket and P.E.T.N. incendiary and steel core
H.E.I. (fuzed Fuzeless): Brass jacket and P.E.T.N. incendiary and steel core
Tracer: CuNi jacket and Steel core
A.P. (Italian): Gilding metal jacket and Lead tip - steel core

As you might have suspected, the 12.7x81mm cartridge was copied from an Italian design.

Colors and markings were:
Ball: Red
A.P.T.: Black or green and white
H.E.I. fuzed: White
H.E.I. fuzeless: Purple
H.E.I. fuzed (Italian): Red, blue or green body
Tracer: Green
A.P. (Italian): Black tip on the nose


This ammunition was copied by the Japanese from the Italians.  Of the two H.E.I. fuzed rounds, one is Italian and the other is a Japanese copy of it.  The Japanese H.E.I. fuzed differs from the Italian round in that the fuze used is of two-piece construction instead of one.  This ammunition is packed in 10-round cartons and is reloaded into metal link belts for use.

Type 97 and Type 98 20mm Ammunition

20mm rounds were used by 4 different Army guns, with the Type 97 round being used in the Type 97 antitank gun, the Ho-1 (flexible) cannon and the Ho-3 (fixed) cannon, while the Type 98 round was used in the dual-purpose Type 98 gun.  The Type 97 was 124mm in case length, and the Type 98 was 142mm.  Both cases were made of drawn brass and were rimless.  The case is crimped to the projectile by three long crimps and sealed by a clear lacquer.

Propellant: The propellant is graphited smokeless powder made in single perforated cylindrical grains approximately 1.5mm in diameter and 3mm in length.  The weight of the propellant in the small case is 35.8 grams and, in the large case, 58.9 grams.

20mm (20x142mm) High-Explosive Tracer Projectile

Overall Length: 20.8 cm
Length of projectile: 81.3mm
Weight of projectile: 128.8 grams
Filling: Cyclonite, tracer composition

Color and markings: Black body with yellow band just aft of bourrelet and white badn forward of rotating band.

Fuzing: Type 93 small instantaneous fuze

Used in: Type 98 antiaircraft/antitank gun

This projectile is made of steel with two cavities separated by a septum.  The round is characterized by a sharp bourrelet.

Next Time: 20mm Ammunition continued...

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