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

A radial delay blowback mechanism for attenuating discharge forces resulting from firing of a projectile from a cartridge, the cartridge further including a cartridge case, comprising:

• a bolt and a carrier incorporated into a receiver of a firearm having a barrel, a trigger actuated firing pin supported within the carrier;
• a cam pin extending from the bolt and seating through a slot configured within the carrier, said pin abutting against a first location of said slot when the bolt is in a set position at a beginning of a discharge cycle with the cartridge chambered and awaiting the discharge cycle;
• a combined radial and axial pocket configured within the upper receiver and which seats an end of said cam pin when the bolt is in the set position;
• said combined radial and axial pocket configured within the receiver being configured within an upper mounted bolt carrier key;
• a plurality of radial bolt lugs configured at a forward end of the bolt;
• upon initiating the discharge cycle, expanding gas forcing the cartridge case rearward into an end face of the bolt, causing the bolt to accelerate axially rearwardly concurrent with the projectile of the cartridge traveling through and out an end of the barrel, the bolt initially displacing relative to the barrel along an interface between said pin and a side wall defining the upper receiver pocket concurrent with said pin traveling within said circumferentially directed slot to convert a portion of the axial acceleration into a rotation of the bolt, the carrier is caused by the bolt to axially displace as the bolt rotates within the carrier, said lug subsequently separating from said rear end extension of the barrel;
• and
• the bolt and carrier retaining sufficient inertia following separation from the barrel to permit successive rearward and forward return displacement to complete the discharge cycle and reload a subsequent cartridge.

A radial delay blowback mechanism for attenuating discharge forces resulting from firing of a projectile from a cartridge, the cartridge further including a cartridge case, comprising:

• a bolt and a carrier incorporated into a receiver of a firearm having a barrel, a trigger actuated firing pin supported within the carrier;
• a cam pin extending from the bolt and seating through a circumferentially directed slot configured within the carrier, said pin abutting against a first location of said slot when the bolt is in a set position at a beginning of a discharge cycle with the cartridge chambered and awaiting the discharge cycle;
• a combined radial and axial pocket configured within the upper receiver and which seats an end of said cam pin when the bolt is in the set position;
• a plurality of radial bolt lugs configured at a forward end of the bolt;
• a mating angular profile with a rear end extension of the barrel during cycling of the bolt to a pre-cartridge discharge position so that the bolt is seated with but not locked to the barrel;
• said mating angular profile defined along opposing contacting surfaces between said lugs and said mating profile further comprising said bolt lugs each having a forward angled edge;
• upon initiating the discharge cycle, expanding gas forcing the cartridge case rearward into an end face of the bolt, causing the bolt to accelerate axially rearwardly concurrent with the projectile of the cartridge traveling through and out an end of the barrel, the bolt initially displacing relative to the barrel along an interface between said pin and a side wall defining the upper receiver pocket concurrent with said pin traveling within said circumferentially directed slot to convert a portion of the axial acceleration into a rotation of the bolt, the carrier is caused by the bolt to axially displace as the bolt rotates within the carrier, said lug subsequently separating from said rear end extension of the barrel;
• and
• the bolt and carrier retaining sufficient inertia following separation from the barrel to permit successive rearward and forward return displacement to complete the discharge cycle and reload a subsequent cartridge.