KAK AR15 bolt assembled for 450 Bushmaster and 458 SOCOM. Assembled bolt only. Bolt manufactured from 9310 steel with outside diameters ground to tight tolerances, MPI tested, with nitride finish. Extractor made from 4140 steel, fully machined, phosphate coated. Ejector made from S7 tool steel, ground and heat treated. Weight: 1.44 oz.