Radial delayed blowback operating system for a firearm including a recoil discharge force attenuation interface between a cam pin and a clearance pocket configured within an upper receiver of the firearm

Abstract

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.