This .308 BCG works on the SR25 platform, AM-10, DPMS, POF, CMMG etc. Carriers are Chrome Lined and made from 8620 steel, The Bolt is made from 9310 steel. Each Bolt is shot peened and MPI tested and Phosphate Coated. Each Carrier has a Chrome Lined Gas Key which is staked in the proper fashion. Includes Cam Pin, Chrome plated Firing Pin and Retaining Pin, ready to drop in your Upper!!