Complete .223/5.56mm Bolt Bolt Left Hand. Features a 9310 steel bolt, heat treated, hard turned and shot-peened 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. Head spaced to Satern, Lilja, Precision Firearms,Proof Research Barrels, X-Caliber, Wilson Combat, and Noveske Rifleworks.