F-1 Firearms DuraBolt Black direct impingement full auto rated AR10 bolt carrier group is compatible with MIL-SPEC receivers and associated components. The DuraBolt Black is enhanced through Chemical Vapor Deposition (CVD) technology and is the hardest, smoothest, and most wear resistant carrier group available. The DuraBolt Black offers the lowest coefficient of friction on the market at .01 after our micro finishing process.

Carpenter 158 bolt, ground after heat treat, MPI and HPT
9310 steel carrier, ground after heat treat