This Surgeon 1086 long 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.Action Material:4140 Chrome Moly 38-40Rc in whiteLength:8.975"Thread:1-16 16UN 3BThread Length:.954"Action Profile:Round BottomWeight:2lbs 5ozLoading Port Length:3.8"Ejection Port Length:3.35"Bolt Material:4140 Chrome Moly 38-40Rc and Ion Nitrided