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.

In some examples, a guide rod can include: a first shaft that includes a first aperture at a first end, a second shaft positioned within the aperture of the first shaft, a sleeve with a second aperture through an interior portion of the sleeve to receive the first shaft, and a gear mechanism positioned within the first aperture to interact with the second shaft and the sleeve when the sleeve changes position along the first shaft.

In some examples, a guide rod can include: a first shaft that includes a first aperture at a first end, a second shaft positioned within the aperture of the first shaft, a sleeve with a second aperture through an interior portion of the sleeve to receive the first shaft, and a gear mechanism positioned within the first aperture to interact with the second shaft and the sleeve when the sleeve changes position along the first shaft.

A bolt assembly is provided for a firearm. The bolt assembly comprises a block adapted to connect to a firearm frame and a bolt carrier adapted to reciprocate within the frame. The bolt assembly comprises a support element between the block and the bolt carrier. The support element is adapted to reciprocate within the frame with respect to the cap and with respect to the bolt carrier. The first and second spaced apart parallel rods are connected to the cap and extending from the cap. The bolt carrier defines a pair of spaced apart bores receiving the rods. A first spring is interposed between the block and the support element, a second spring is received on the first rod, and a third spring is received on the second rod.

A bolt assembly is provided for a firearm. The bolt assembly comprises a block adapted to connect to a firearm frame and a bolt carrier adapted to reciprocate within the frame. The bolt assembly comprises a support element between the block and the bolt carrier. The support element is adapted to reciprocate within the frame with respect to the cap and with respect to the bolt carrier. The first and second spaced apart parallel rods are connected to the cap and extending from the cap. The bolt carrier defines a pair of spaced apart bores receiving the rods. A first spring is interposed between the block and the support element, a second spring is received on the first rod, and a third spring is received on the second rod.

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.

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.

The present device is a shortened recoil system designed to replace the AR-15 type recoil system, comprising the standard recoil systems of many commonly used rifles including the AR-10, AR-15, M-16 and M-4. This shortened recoil system removes or replaces the parts of the traditional recoil system located in the stocks of these rifles and place the entire recoil system within the receiver, while maintaining the alignment of the recoil system with the barrel of the rifle. A major advantage of the present system is that it allows the rifle to be fired with a folded stock or even with no stock at all, as no part of the present recoil system is located within the stock.