Patent ID: 8746126

Claim:
An annular piston system for a firearm, the annular piston system comprising: a barrel having a plurality of sections lengthwise, a first section of the barrel having a first outer diameter, a second section of the barrel adjacent the first section and having a second outer diameter, a third section of the barrel adjacent the second section and having a third outer diameter, a distal end of the first section being a first distal end of the barrel, a distal end of the third section being a second distal end of the barrel opposite the first distal end of the barrel, the second section having at least one gas port hole traversing through a wall thickness thereof, wherein the first distal end of the barrel includes a threaded portion, and wherein the second distal end of the barrel includes a threaded portion; a gas block assembly disposed annularly around the first and second sections of the barrel, the gas block assembly adjustably controlling an amount of gas flowing out of the barrel through the at least one gas port hole; a piston disposed annularly around the third section of the barrel, the piston configured to move longitudinally along the barrel in response to being pushed by the gas flowing out of the barrel; a spring disposed annularly around the third section of the barrel and coupled to the piston, the spring configured to limit a distance that the piston moves longitudinally along the barrel when the piston is pushed to move towards the second distal end of the barrel by the gas flowing out of the barrel; a muzzle device that mates with the threaded portion on the first distal end of the barrel; a barrel extension that mates with the threaded portion on the second distal end of the barrel; two or more piston rods coupled to the piston and disposed between the spring and the barrel; a piston locking ring disposed annularly around the barrel and the piston rods and coupled to the piston; and a barrel locking device disposed annularly around the barrel extension, wherein a first end of the spring is coupled to the piston locking ring and a second end of the spring opposite the first end is coupled to the barrel locking device.