Cont OTCM 37119 dtd 1958.
The cartridge consists of a perforated metal cartridge case crimped to a hollow steel projectile. The cartridge case contains a plastic liner which is filled loosely with propellant. An igniter charge is positioned on top of the propel-lant. A percussion primer is fitted in the base, with an igniter tube extending through the propelling charge. The projectile is fitted with either a point detonating or mechanical time, superquick fuze in the nose, and is filled with TNT. The rotating band near the base is pre-engraved to match the bore rifling of the weapon. A bourrelet at the rear of the ogive and another forward of the rotating band are provided as bearing surfaces for the projectile in the rifle bore.
When the weapon firing pin strikes the primer, flame from the primer black powder ignites the propelling charge. The burning pro-pellant generates rapidly expanding gases to propel the projectile through the rifle barrel and to the target. Recoil is eliminated because some gas pressure escapes through the perforated cartridge case, and is controlled by apertures in the rifle breech-block. The rotating band engages the bore rifling to spin the projectile for stability in flight. On impact, fuze functioning detonates the high explosive, producing blast and fragmentation.
Difference Between Models:
M309 has a paper-lined cartridge case, and does not have the igniter charge on top of the propelling charge.
Weight with fuze 22.37 lb
Length with fuze 28.92 in.
Cannon used with M20
Body material -------------------- Forged steel color -------------------------------- Olive drab w(yellow markings
Components: Cartridge case:
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