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Japanese

7.7 mm Explosive Cartridge

This fixed round of ammunition consists of a brass cartridge case and a high explosive projectile. The semi-rimless case is tapered, forming a neck which fits over the projectile. The top of the neck is coned into the cannelure of the bullet. The base of the case is recessed to take a simple percussion type […]

Japanese Explosive Cartridge

This fixed round of ammunition consists of a brass cartridge case and a high explosive projectile. The semi-rimless case is tapered, forming a neck which fits over the projectile. The top of the neck is coned into the cannelure of the bullet. The base of the case is recessed to take a simple percussion type primer, and the rest of the case is filled with a propelling charge of graphited nitro-cellulose grains, about half of which, in the specimens examined, had a very fine axial perforation.

The brass projectile is cylindrical in shape with a truncated ogival nose. It contains a brass inner compartment, ogival in shape and open at the base, and a hammer consisting of a lead antimony plug encased in a brass sheath. The rear of the projectile is also open, the walls being turned in to retain the hammer. Both the main projectile and the inner compartment. are filled with the explosive charge, a mixture of PETN and RDX. A white felt washer pressed into the base of the inner compartment protects the explosive charge from the effect of setback when the round is fired.

When the projectile strikes a target, the hammer in the rear end sets forward crushing the explosive against the walls of both the inner and main compartments, causing the projectile to explode.

SPECIFICATIONS

Caliber        7.7 mm (.303 in.)
Weight of complete round 26.15 grms.—.915 oz.
Length of complete round 3 3/32 ins.
Length of cartridge case 2 9/32 ins.
Weight of cartridge case (without percussion cap) 14.93 grms.—.523 oz.
Weight of projectile 10.69 grms.—.374 oz.
Length of projectile 1 15/32 ins.
Maximum diameter 0.310 in.
Thickness of main compartment walls 0.021 in.
Weight of main compartment 2.95 grms.—.103 oz.
Thickness of inner compartment walls 0.008 in.
Weight of inner compartment 0.20 grms.—.007 oz.
Height of inner compartment 0.390 in.
Length of hammer 0.700 in.
Weight of hammer 6.65 grms.—.233 oz.
Diameter of hammer 0.258 in.

Japanese: p. 221 (April 1, 1945)