Nickel Boron AR10 / .308 Bolt Carrier Group - BCG This MPI 9310 NiB plated 308 BCG is a perfect choice for your AR10 or any other large frame DPMS pattern AR build. Made from enhanced 9310 steel bolt and 8620 tool steel carrier, this shot-peened BCG is one of the most reliable, well-made carrier groups available. It comes with a lifetime warranty, too, making it ideal for any enthusiast. Enhanced 9310 steel (bolt) 8620 tool steel (carrier) Shot-peened, MPI bolt Mil-spec extractor spring, black extractor insert & Viton O-ring Tool steel extractor Shrouded firing pin Mil-spec 4130 steel gas key attached with Grade 8 hardware and properly staked All BCG components pre polished before being plated with UCT's Exclusive EXO Technology and then post polished for an incredible shine. SKU: RTB308-011 UPC: 860006521499 Maximum Purchase: 10 units