The F-1 Firearms DuraBolt Bolt Carrier Group is a full auto rated M-16/M4 bolt carrier group for use in Mil-Spec AR-15 receivers. The bolt carrier and bolt are ground after heat treat to ensure tolerances. The carrier is made from 8620 steel and the bolt is made from Carpenter 158 steel and MPI and HPT tested. Made in the USA.
Finish: Gold Nitride Finish