AO Precision C158 SP/HPT/MPI 5.56 Black Nitride Bolt Carrier Group

AO Precision C158 SP/HPT/MPI 5.56 Black Nitride Bolt Carrier GroupAO Precision has provided BCGs to large military contractors such as FN America and large commercial retailers who re-brand and sell these at a considerable mark-up.Bolt Machined from Carpenter Technology No. 158 alloy. Heat treated Shot peened per ASTM B851/SAE AMS2430S Individually High Pressure Tested (test fired) HP proof testing, 100% using a high pressure M197 or SAAMI commercial equivalent, without evidence of failure Individually Magnetic Particle Inspected after Initial Test Fire Black Nitride FinishExtractor 4140 Steel per ASTM A108, cold drawn and stress relieved BHN 187-22 Phosphate Finish Extractor Spring Black Extractor Insert Viton O-RingCarrier Machined from AISI 8620 aircraft quality alloy per ASTM A108/A322-13 Full Mass M16 Profile Stress Relieved Black Nitride FinishGas Key Machined from 4130 chromoly steel alloy per ASTM A108/A322-13 Grade 8 Hardware Properly Staked Hard Chrome Internal Permatex sealed