The Ideal Big-Bore Bolt Carrier Group The Brownells Complete .308 Bolt Carrier Group is designed to operate reliably in DPMS LR-308 pattern rifles chambered in .308, .243, 7mm-08, .338 Federal, .260 Remington, 6.5mm Creedmoor, or any other cartridge based on the .308 Winchester. These BCGs are manufactured to the same uncompromising standards as our M16-style BCGs. Our Complete .308 Bolt Carrier Group has a bolt machined from robust 9310 steel, heat-treated and shot-peened for superb hardness. The carrier itself is fabricated from hardened 8620 steel. Both are magnetic particle inspected (MPI) to make sure there are no hidden microscopic flaws that could lead to premature failure. Carrier has forward assist notches Extractor is installed with rubber insert and spring Gas key screws are torqued and staked For use in DPMS LR-308 pattern upper receivers only; NOT compatible with Armalite rifles You can get the Brownells Complete .308 Bolt Carrier Group with a hard Black Nitride finish that is exceptionally resistant to surface wear OR a Nickel Boron coating (a dull matte silver) that’s even harder and self-lubricating to boot. Both come complete with firing pin, firing pin retaining pin, cam pin, gas rings, gas key, extractor, and ejector installed. Brownells GunTech™ Note: Unlike BCGs with a traditional Parkerized finish, the carrier on our Black Nitride bolt carrier group is not hard-chromed inside because Nitride is actually harder than industrial chrome plating. Big Book Catalog, Issue:73, Page:018