A firearm operating system includes a firing pin having a first end and a second end. An operating rod assembly includes an operating rod, a lug positioned at a first end of the operating rod, and a firing pin retainer extending from the lug. A bolt carrier includes a bolt carrier pocket structured to receive the firing pin retainer, and a bolt carrier cam pin opening. A bolt is structured to be received in the bolt carrier. The bolt includes a bolt cam pin opening. A cam pin is structured to be positioned through the bolt carrier cam pin opening and into the bolt cam pin opening. The first end of the firing pin extends through a firing pin opening of the cam pin to retain the cam pin. The firing pin retainer of the operating rod assembly engages the second end of the firing pin so as to retain the firing pin.