From the description:
Manufactured by the finest Mil-Spec contractor, these are the best AR rifle bolts we have found. This is the parkerized version of the same bolt carrier group inside every Wilson Combat Custom Rifle.
Parkerized exterior and chrome lined internally, the full-auto carrier includes the proper Mil-Spec gas key that is chrome lined and heat treated per GI specifications. The gas key is secured to the carrier via USGI domestic mfg Grade 8 fasteners and properly staked per Mil-Specs. These properly hardened parts ensure proper gas system functioning.
The bolt assembly is machined from the correct Mil-Spec Carpenter No. 158® steel, shot peened for increased strength and a includes tool steel machined extractor and ejector, appropriate extractor spring, and is HPT (High Pressure Tested) and MPI (Magnetic Particle Inspected).
Last edited by MEW; 10-10-2013 at 2:24 PM..