Test 1773943564785927941 BCM Bolt Carrier Group MPI

BCM's bolt carrier group is the standard against which most mil-spec BCGs are measured, used in BCM complete rifles and favored by military and law enforcement armorers who need a known-quantity component. The bolt is machined from Carpenter 158 steel — the same material specification required by the US military for M16/M4 bolts — rather than the 9310 steel used by most commercial manufacturers. Carpenter 158 has marginally higher toughness in the lug shear direction under extreme fatigue conditions. The bolt is Magnetic Particle Inspected (MPI) and High Pressure Tested (HPT) to mil-spec requirements, and individual bolt results are documented and tracked. The carrier key is properly staked and the carrier interior is chrome-lined for easy cleaning.