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

Right here is a True Mil-Spec BCG. This unit is for builders who prefer tried and true manufacturing and aggressive quality assurance testing over fancy coatings, proprietary profiles and laser engraved logos.Bolt Machined from Carpenter Technology No. 158 alloy. Heat treated Shot peened per ASTM B851/SAE AMS2430S Individually High Pressure Tested (test fired) Individually Magnetic Particle Inspected Manganese Phosphate FinishExtractor Tool Steel Extractor Black Nitride Phosphate Finish Mil-Spec O-RingCarrier Machined from AISI 8620 aircraft quality alloy per ASTM A108/A322-13 Full Mass M16 Profile Stress Relieved Hard Chrome Bore Black NitrideGas Key Machined from 4130 chromoly steel alloy per ASTM A108/A322-13 Grade 8 Hardware Properly Staked Hard Chrome Internal Permatex sealedLike all NBS parts, this unit is backed by a lifetime warranty.