A firearm operating system for self-loading firearms includes a bolt body having a forward bolt bearing, a piston and an aft bolt bearing arranged around the bolt body; a bolt carrier slidingly receiving the bolt body in a longitudinally-oriented cylinder, the cylinder extending from a forward end of the bolt carrier into the bolt carrier a predetermined distance, the bolt carrier having a tubular aft carrier bearing, wherein the bolt is slidingly captured in the cylinder of the bolt carrier and borne on the two bearings of the bolt body, wherein the forward bearing of the bolt body is borne on the cylinder of the bolt carrier, wherein the aft bearing of the bolt body is borne on the aft bolt carrier bearing, wherein a gap is formed between the piston and the cylinder, and wherein the piston and the cylinder do not contact each other.