Abstract: A blow-back operating automatic firearm has a sliding mass carried with its bolt carrier assembly to increase the dwell time of the bolt at the breech when the bolt is in battery position for firing. The sliding mass reduces the tendency of the bolt to bounce-off the head end of the seated cartridge, thereby reducing the risk that a misfiring will occur.

Abstract: A cartridge feed tray for belt ammunition is modified to receive shorter ammunition and exclude ammunition of standard length by inclusion of an insert positioned along the forward containment wall of the tray. The insert carries a feed lip that fits through a loading port orifice in the feed tray to direct shorter ammunition downwardly as it is being advanced towards the weapon breach for loading.

Abstract: A training kit is designed for use with a firearm normally having a standard bolt that is provided at the forward end with a bolt recess for receiving and embracing the head end of a standard cartridge. The training kit is provided with a training bolt having a circular recess of a diameter that will not receive and embrace the head end of the standard cartridge thereby limiting placement of a standard cartridge beyond the reach of the firing pin. Rounds of reduced-energy training ammunition are provided with a head end of complementary dimensions that permits the head end to be seated within the recess of a conversion bolt, and therefore fired.

Abstract: A non-toxic primer composition for use in ammunition is provided with a hygroscopic oxidizer which is protected from absorption of water vapor by a water-barrier coating. A preferred oxidizer is potassium nitrate and a preferred coating is nitrocellulose.

Abstract: An automatic pistol converted to fire low energy ammunition in a blow-back mode has a replacement barrel that carries a cam on its upper surface. The weapon slide, as it retires during firing, contacts the cam and rotates the chamber end of the replacement barrel downwardly. This aligns the spent casing for ejection by the ejector, once extracted from the chamber. The slide may carry a removable deflector plate for contacting the cam.

Abstract: A telescopic training round has an inner sealant disc with a central hole to ensure against gas leakage as the casing expands telescopically.

Abstract: A conversion kit for a recoil-operating automatic pistol to convert it to direct blow-back operation utilizes a two piece barrel having chamber and muzzle portions that may be threaded together. The chamber portion is first installed on the receiver by insertion through the injection port, and the muzzle-piece is then threaded to the chamber-piece to complete the assembly of the barrel.

Abstract: A training barrel for conversion of a firearm from normal barrel/slide partial locking operation to unlocked slide blow-back operation has an insert which provides a guide ramp for chambering rounds during the reload cycle. The guide ramp compensates for the absence of rearward displacement of the barrel when the firearm is converted to a training configuration. Such insert may be assembled into the weapon without modification to the slide or frame of said weapon.