Improvements include using 9310 tool steel for the bolt, which is stronger and nitriding the assembly to increase surface hardness, decrease resistance, and have superior corrosion resistance compared to typical chrome and phosphasted bolt carrier groups. All bolts are fully MPI tested to ensure the material is sound and without defects. Bolt lugs are chamfered 45 degrees to ensure reliable action for even the highest pressure hand loads and fast lightweight actions.  Faxon Bolt Carrier Groups are Superfinished to reduce friction, increase smoothness of operation, and reduce fouling. Further, they are full-Auto rated and maintain the trip for full-auto fire control groups and new multi-stage trigger systems. Gas keys use grade 8 fasteners and are fully staked for a lifetime of service.  Technical Specifications 9310 Tool Steel Bolt Full MIL-SPEC Heat Treatment Shot Peened to MIL-SPEC Magnetic Particle Inspection (MPI) Back of Lugs Chamfered for Reliability Spring, Insert, & "Crane" O-Ring Installed Salt Bath Nitrided Bolt & Carrier S7 Extractor Superfinished Carrier Body Full Auto Compatible Forward Assist Serrations