Combustible Ammunition for Small Arms. IV. Development of Improved Obturator Devices for Caseless Ammunition

摘要

An obturator, reusable for approximately 60 firings of 7.62 mm caseless ammunition, was designed, fabricated, and evaluated. This obturator consisted of two metal split rings with a neoprene O-ring positioned between them. A 7.62 mm caseless test weapon (Model 4) was designed and fabricated for this investigation, and a Springfield 1903 rifle was similarly modified for shoulder firing 7.62 mm caseless ammunition before the U. S. Army Infantry Board during June 1962. A combination obturator/firing pin projectile (designated 'Bulpin') was designed, fabricated, and evaluated for caliber .30 caseless solid propellant ammunition. Two such Bulpin projectiles, one in front of a bore-size caseless charge containing a combustible primer and one behind it for ignition and obturation, provided a solid propellant caseless system which used a new firing pin and seal for each firing. After each firing, the rear projectile was pushed forward by the next Bulpin round for use as the next projectile. There are indications that, in caseless solid propellant ammunition, the increased ratio of propellant charge length to propellant charge diameter results in lower projectile velocity and higher peak pressure and that increased molding pressure in the forming of the propellant results in higher velocity and higher peak pressure. (Author)