A firearm including a receiver, a barrel, a breech bolt assembly, and a trigger assembly. The bolt assembly has a bolt including a body portion, a lug portion, and a firing pin bore. The lug portion includes outward extending lugs, a cartridge recess, and an off-center hole. The bolt assembly also includes an extractor and an ejector pin. At least some of the lugs on the lug portion of the bolt have a tapering outer face so that a rearward face of the respective lug is taller than a forward face of the respective lug. In another aspect, at least some of the lugs on the lug portion of the bolt have tapering side faces so that a rearward face of the respective lug is wider than a forward face of the respective lug.

A weapon for firing cased telescoped (CT) ammunition includes a barrel, a chamber member and a carrier assembly. The chamber member defines a chamber for a CT round for firing, and translates between a firing position aligned with the barrel and an ejection/loading position. The chamber member is spring-biased toward the firing position. Dual-feed structure provides for both a magazine mode as well as a belt feed mode of operation.

A weapon for firing cased telescoped (CT) ammunition includes a barrel, a chamber member and a carrier assembly. The chamber member defines a chamber for a CT round for firing, and translates between a firing position aligned with the barrel and an ejection/loading position. The chamber member is spring-biased toward the firing position. Dual-feed structure provides for both a magazine mode as well as a belt feed mode of operation.

A delayed rotary blowback mechanism integrated into a firearm bolt and carrier subassembly. A plurality of radial locking lugs are configured at a rear end of the bolt and seat within a mating profile of an upper receiver interior or integrated trunnion in a fully chambered position. A plurality of chamfered locations are configured between the lugs and a receiving profile in the barrel or trunnion for influencing linear to rotational motion of the bolt. A cam pin extends upwardly from the bolt and seats through a circumferentially directed slot configured within the bolt carrier. Upon initiating of the discharge cycle, signaled by the round traveling through and out the end of the barrel, the chamfered configuration results in the bolt and cam pin rotating within the carrier and the lugs subsequently separating from the receiver or trunnion, with the bolt and associated carrier retaining sufficient inertia to cycle through the discharge cycle to the set position concurrent with reloading a subsequent cartridge.

A delayed rotary blowback mechanism integrated into a firearm bolt and carrier subassembly. A plurality of radial locking lugs are configured at a rear end of the bolt and seat within a mating profile of an upper receiver interior or integrated trunnion in a fully chambered position. A plurality of chamfered locations are configured between the lugs and a receiving profile in the barrel or trunnion for influencing linear to rotational motion of the bolt. A cam pin extends upwardly from the bolt and seats through a circumferentially directed slot configured within the bolt carrier. Upon initiating of the discharge cycle, signaled by the round traveling through and out the end of the barrel, the chamfered configuration results in the bolt and cam pin rotating within the carrier and the lugs subsequently separating from the receiver or trunnion, with the bolt and associated carrier retaining sufficient inertia to cycle through the discharge cycle to the set position concurrent with reloading a subsequent cartridge.

A delayed blowback mechanism integrated into a firearm bolt and carrier subassembly. A cam pin extends from the bolt and, upon initiation of the cartridge discharge cycle, engages a guiding clearance or pocket configured within the firearm upper receiver for providing recoil and discharge force attenuation in a radial delayed fashion during cycling of the bolt carrier group. Recoil attenuation between the cam pin and upper receiver clearance can be provided alone or assisted by chamfer or angled contour to either or both of the radially projecting and rear contact surfaces of the bolt locking lugs and the opposing inward projections configured within the barrel extension grooves. In any variant, the bolt and associated carrier retain sufficient inertia to cycle through the discharge cycle to the set position concurrent with reloading a subsequent cartridge.

A delayed blowback mechanism integrated into a firearm bolt and carrier subassembly. A cam pin extends from the bolt and, upon initiation of the cartridge discharge cycle, engages a guiding clearance or pocket configured within the firearm upper receiver for providing recoil and discharge force attenuation in a radial delayed fashion during cycling of the bolt carrier group. Recoil attenuation between the cam pin and upper receiver clearance can be provided alone or assisted by chamfer or angled contour to either or both of the radially projecting and rear contact surfaces of the bolt locking lugs and the opposing inward projections configured within the barrel extension grooves. In any variant, the bolt and associated carrier retain sufficient inertia to cycle through the discharge cycle to the set position concurrent with reloading a subsequent cartridge.

An ambidextrous straight-line manually operated bolt with rotatable closing slugs has a bolt body or casing having a square cross section and housing inside it forming a hollow main cylinder with 3 closing lugs on its head, a second hollow cylindrical body that fits inside the first cylinder, the top half of which is open at the front and on the sides of which rest two flat gears, multiplier gears that act on the flat gears, and a firing pin or striker that passes in between the two hollow cylindrical bodies.

An ambidextrous straight-line manually operated bolt with rotatable closing slugs has a bolt body or casing having a square cross section and housing inside it forming a hollow main cylinder with 3 closing lugs on its head, a second hollow cylindrical body that fits inside the first cylinder, the top half of which is open at the front and on the sides of which rest two flat gears, multiplier gears that act on the flat gears, and a firing pin or striker that passes in between the two hollow cylindrical bodies.

A locked breech rotating bolt pistol caliber operating system for use with a semi-automatic or fully automatic firearms is described that is retro fit capable and is compatible with many existing AR15 type lower receivers that utilize pistol caliber magazines. The operating system includes an upper receiver that includes a fixed ejector to eject spent casings to minimize the likelihood that the firearm will jam.