A Bolt-Carrier Group Purpose-Built to Run Reliably in Your AR-15
Whether you're looking to finish off a new AR-15 build or you need a spare bolt-carrier group to have on-hand as a ready replacement (always a good idea), Brownells has you covered with its AR-15 Bolt Carrier Group. This ready-to-roll BCG is built to provide dependable operation in any AR-15 chambered in 5.56 NATO, .223 Remington or 300 Blackout.
Each Brownells AR-15 Bolt-Carrier Group features a bolt machined from 9310 tool steel, which is heat-treated and shot-peened. The carrier itself is machined from 8620 hardened steel. Both of these components, as well as every other part in the bolt-carrier group, are finished in a nitride coating. Every bolt is magnetic-particle inspected and features a torqued-and-staked gas key.
With each Brownells AR-15 Bolt-Carrier Group, you'll receive the bolt, bolt carrier, gas key, firing pin, cam pin, firing pin retaining pin and an extractor with the necessary spring and rubber insert. This bolt-carrier group will work with any cartridge based on the 5.56 NATO case, and it is not designed for use in full-auto lower receivers.
Big Book Catalog, Issue:73, Page:017