The Radian bolt carrier is manufactured from case hardened 8620 steel with properly staked 4130 steel gas key. The accompanying bolt is case hardened 9310 steel, shot peened, HPT and MPI tested, and finished in a self-lubricating polished black nitride. Bolt lugs are CNC ground following heat treatment to insure the greatest accuracy possible.FeaturesProperly staked gas keySelf-lubricating polished finishComplete Bolt Carrier Assembly, Drop-in readyProperly Staked Gas Key, Bolt is Shot Peened, HPT & MFI Tested