Abstract: A barrel positioning spring moves a barrel in a blow-back operating pistol earwardly when the slide recoils in order to position the chamber on the barrel to receive a further cartridge with the return of the slide. This spring in a Colt(.TM.) .45 caliber pistol may be seated on the recoil spring guide rod present beneath the barrel. A removable loading ramp extension is fitted to the frame in the space between the chamber end and the next cartridge to receive such cartridge as it is being chambered by the returning slide.

Abstract: A barrel for an automatic firearm which cycles on recoil action is provided with a transverse pin extending across the top of the rearward portion of the chamber. This pin nests within the extraction groove of a cartridge sing during firing. On cycling, the transverse pin deflects the spent case downwardly towards an ejector which effects ejection of the casing.

Abstract: A two part cartridge has a rearwardly recoiling inner piston and a choked orifice at its forward end to develop a blow-back thrust that will cycle a recoil operated automatic firearm. The piston itself may serve to contain propellant and preferably contains all propellant within the cartridge.

Abstract: A low toxicity primer composition is provided incorporating a heavy-metal free primer explosive sensitizer, metallic fuel and an oxidizer selected from an oxidizer selected from the group consisting of cesium nitrate, strontium sulfate, strontium oxalate, sodium oxalate, nitroguanadine, guanadine nitrate, penthrite, zirconium oxide, and mixtures thereof.

Abstract: A projectile for firing from a self-loading firearm is provided that will rmit the self-loading mechanism to function while delivering a targeting projectile of reduced range and striking capacity. These latter characteristics may be varied in accordance with a designer's preference.

Abstract: A cartridge 10 for low-mass, frangible projectiles 60 comprises a cartridge ase 12 having a primer 14 at its base and a sabot 30 or piston 30 at its mouth. The piston 30 can be provided with longitudinal orifices 44, diagonal orifices, 44a, grooves 64 or any combination of orifices and grooves. The projectile 60 is inserted into a cylindrical recess 46 in the front portion of the sabot 30. The orifices 44 are in communication with this recess 46 to permit propellant gas to bleed through and accelerate the projectile 60 upon ignition. The case 12 and the sabot 30 can be provided respectively with a crimp 24 and a stepped portion 48 in order to limit travel of the sabot 30 out of the case.

Abstract: The disclosure herein describes a frangible practice ammunition comprising a compacted mixture of fine copper powder and of a thermoplastic resin selected from the group consisting of nylon 11 and nylon 12. The mixture which is compacted by injection molding, has at least 90% by weight of copper and a specific gravity of 5.7.