Bolt Carrier Group Features An AR-15 bolt carrier group is a piece of a firearm that houses many important parts such as the firing pin gas key cam pin extractor and bolt. With all these pieces working together the BCG can grab and feed another round out of a detachable magazine chamber and engage the cam groove engage with the locking lugs in the barrel fire and extract a spent cartridge. During the extraction of a cartridge the BCG works to absorb the force of the explosion by expanding gas in the carrier. During this process gas is tapped off from the barrel and is sent into the cup inside of the gas key creating an inertial force that sends the Bolt Carrier Group back into the buffer tube which helps to minimize the recoil of your gun when firing and the cycle will repeat for subsequent shots. This BCG is an AR-15 compatible design allowing use with .223 Remington 5.56 NATO .300 Blackout & .350 Legend cartridges. The standard AR-15 bolt carrier is also machined from 9130/8620 Steel with a Nitride finish. This BCG comes with the ability to be fully-auto compatible and also features forward assist notches. MPI testing has also been done to ensure that there are no structural flaws to this BCG. Bolt Carrier Group Specifications Brand: TacFire Bolt: 9130 Steel Carrier: 8620 Steel MPI Tested and Shoot Peened