The F-1 Firearms DuraBolt Black Nitride direct impingement full auto rated M16/M4 bolt carrier group, for use in AR15 platforms, is compatible with mil-spec receivers and associated components. The bolt carrier and bolt are ground after heat treat to ensure tolerances.
- CRN Coated, Silver
- Carpenter 158 bolt that is ground after heat treat
- 8620 Steel Construction
