BCM (MPI) complete bolt carrier group is fully assembled.

Bolt carrier group (auto version) f your AR15, M16, or M4. Parkerized exterior and chrome lined inside carrier. Machined to USGI specifications. This M16/M4 carrier includes the proper Mil-Spec gas key. Gas key is chrome lined and heat treated per GI specifications. Gas key is secured to carrier via USGI domestic mfg Grade 8 fasteners and properly staked per Mil-Specs. These properly hardened parts insure a strong staking and proper gas system functioning.

The bolt assembly is shot peened for increased strength, includes tool steel machined extractor, BCM Extractor Spring, and is MPI (Magnetic Partical Inspected).

SPECS:

MPI Bolt (Magnetic Particle Inspected)
Shot Peened Bolt
Chrome Lined Carrier (AUTO)
Chrome Lined Gas Key
Gas Key Hardened to USGI Specifications
Grade 8 Hardened Fasteners
Key Staked Per Mil-Spec
BCM Extractor Spring
Black Extractor Insert
Mil-Spec Crane O-Ring