Premiere Firearms PF-15 16" AR Rifle 6000 series billet lower and upper with ambidextrous charging handle. Includes improved muzzle device. Carriers are manufactured from 8620 and are precision machined in one operation, heat-treated, and ground to a final specification of +/-0.0005". Our standard bolts and carriers are offered to military specification dimensions and processes but can be modified to customer specifications to achieve higher performance standards. Bolts are manufactured from 9310 material and are manufactured in a single operation, ensuring proper machine indication and reducing the opportunity for dimensional error. They are heat treated, and then ground to a final specification of +/-0.0005".