Faxon Firearms Superfinished 6.5 Grendel/ARC Bolt Carrier Group Gunner Lightweight Nitride Black. Improvements include using 9310 tool steel for the bolt 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. Specifications for Faxon Firearms Superfinished 6.5 Grendel/ARC Bolt Carrier Group: Manufacturer: Faxon Firearms Color: Black Finish: Nitride Caliber: 6.5mm Grendel Package Contents: Faxon Firearms Superfinished 6.5 Grendel/ARC Bolt Carrier Group Faxon Firearms FF65GBCGCNITRIDE-LW: Superfinished 6.5 Grendel/ARC Bolt Carrier Group Gunner Lightweight Nitride Black