We don’t just machine out the bolt face on a standard 5.56mm bolt leaving a thin wall and weak lugs. We machine it right from the start and you use your STANDARD AR15 firing pin. As with all of our bolts we finish grind all critical diameters “After” heat treat resulting in a bolt that is true and square to the bolt face for 100% lug contact. Other calibers coming soon. Made from 9310 steel and heat treated to mil spec.