Mercury Precision AR-15 5.56/.223, HPT/MPI Tested, Full Auto Profile, 9310 Steel Nitride Bolt Carrier Group

An AR-15 bolt carrier group is a piece of a firearm that houses many key 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 the detachable magazine chamber. During the extraction of a cartridge, the BCG works to absorb the force of the explosion by expanding gas in the carrier. Throughout this process, gas is tapped off from the barrel and sent into the cup inside of the gas key which creates an inertial force that sends the Bolt Carrier Group back into the buffer tube. This entire process helps to reduce recoil.