This Surgeon Left Hand 591 short, repeater action has .473" bolt face diameter to fit a .308 Winchester with a Remington style extractor. It has a .25" recoil lug, tactical bolt knob, 20 MOA 1913 picatinny rail, side mounted bolt stop to prevent accidentally releasing, an anti-jam rail to prevent a round from lodging in the raceway, and an anti-bind rail.