A spring system for blowback action is provided with a control piece (2) and pusher piece (3) supported so that it can be displaced on the guide rod (7). On its end, a buffer (4) is arranged with a buffer spring (6). The guide rod (7) is also used for guiding the closing spring (8). Between the control piece (2) and pusher piece (3) there are five rollers (10) in a recess (9) of the guide rod (7), and these rollers cause a delay of the action during the blowback after the discharge of a shot.

An upper receiver for the one family of firearms allows for the use of a bolt of another firearm family in the firearm action. In the depicted embodiment, an AR-15 bolt and its carrier group are simple drop-in with only the addition of a sear plate, clamp, and an insert into the bolt carrier group. The depicted receiver is designed to also prevent its use on the semi-automatic variants of the MAC family.

An upper receiver for the one family of firearms allows for the use of a bolt of another firearm family in the firearm action. In the depicted embodiment, an AR-15 bolt and its carrier group are simple drop-in with only the addition of a sear plate, clamp, and an insert into the bolt carrier group. The depicted receiver is designed to also prevent its use on the semi-automatic variants of the MAC family.

A system for firing reduced energy cartridges from a modern sporting rifle utilizes a bolt assembly weighing less than a conventional bolt assembly for such rifles and utilizes blow back for cycling the bolt assembly rather than gas operation. A bolt insert in a polymer bolt carrier of the bolt assembly has a projection that fits within a recess on the rear face of reduced energy cartridges. The reduced energy cartridges having a polymer casing, a rimfire power load for propellant, the power load recessed from the rear face of the casing. Tuning the bolt may comprise adjusting the weight of the bolt or the sliding resistance of the bolt assembly in the upper receiver. The bolt may be formed by metal injection molding with a polymer bolt carrier attached thereto.

A system for firing reduced energy cartridges from a modern sporting rifle utilizes a bolt assembly weighing less than a conventional bolt assembly for such rifles and utilizes blow back for cycling the bolt assembly rather than gas operation. A bolt insert in a polymer bolt carrier of the bolt assembly has a projection that fits within a recess on the rear face of reduced energy cartridges. The reduced energy cartridges having a polymer casing, a rimfire power load for propellant, the power load recessed from the rear face of the casing. Tuning the bolt may comprise adjusting the weight of the bolt or the sliding resistance of the bolt assembly in the upper receiver. The bolt may be formed by metal injection molding with a polymer bolt carrier attached thereto.

A delayed rotary blowback mechanism integrated into a firearm bolt and carrier subassembly. A plurality of lugs are configured at a rear of the bolt and seat within a mating profile of a barrel extension of the firearm in a fully chambered position. Chamfered locations are configured between the lugs and a receiving profile in the barrel extension 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 of a fired round traveling 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 barrel extension. The bolt and carrier retain sufficient inertia to cycle through the discharge cycle concurrent with reloading a subsequent cartridge.

A delayed rotary blowback mechanism integrated into a firearm bolt and carrier subassembly. A plurality of lugs are configured at a rear of the bolt and seat within a mating profile of a barrel extension of the firearm in a fully chambered position. Chamfered locations are configured between the lugs and a receiving profile in the barrel extension 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 of a fired round traveling 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 barrel extension. The bolt and carrier retain sufficient inertia to cycle through the discharge cycle concurrent with reloading a subsequent cartridge.

A weapon system is provided. The weapon system includes a receiver and an operating group. The operating group includes a bolt at least partially housed within the receiver; an operating rod (op-rod) assembly arranged to axially translate within the bolt. The operating group also includes a carrier assembly, a bolt assembly, and a recoil assembly. The system further includes a hinge or pivot joint at a connection between the recoil assembly and the carrier assembly, a firing pin lock, an elastomeric cone interface between the bolt assembly and the receiver, a hollowed out piston, and/or tapering on the lug of the bolt assembly.

A weapon system is provided. The weapon system includes a receiver and an operating group. The operating group includes a bolt at least partially housed within the receiver; an operating rod (op-rod) assembly arranged to axially translate within the bolt. The operating group also includes a carrier assembly, a bolt assembly, and a recoil assembly. The system further includes a hinge or pivot joint at a connection between the recoil assembly and the carrier assembly, a firing pin lock, an elastomeric cone interface between the bolt assembly and the receiver, a hollowed out piston, and/or tapering on the lug of the bolt assembly.

Provided is a side charging handle system for an AR-pattern firearm with an upper receiver having an internal longitudinal bore for receiving a bolt carrier assembly for longitudinal reciprocation therein, a side longitudinal guide slot, and a side charging handle having an engagement pin extending through guide slot to engage the bolt carrier assembly.