Complete 6.5 Grendel Bolt Nickel Boron Features a 9310 steel bolt, heat treated, hard turned and shot-peened, Nickel Boron coated, for increased surface strength and durability, and an extractor booster to ensure reliable cycling during rapid semi-auto or full-auto fire. Parts are magnetic particle inspection tested in batches to ensure it’s free from imperfections that can lead to premature failures. Bolt has a .136 head spacing commonly referred to as the type 2 bolt. We also offer a type 1 bolt or 7.62x39 withe a .125 head spacing. Head spaced to Satern, Lilja, Precision Firearms,Proof Research Barrels, X-Caliber, Wilson Combat, and Noveske Rifleworks.