What Thread Pitch Is my Aero Barrel? 9mm, 5.56 NATO/223 1/2x28 6 Creedmoor, 6.5 Grendel, 6.5 Creedmoor, 300 Blackout, 308 WIN 5/8x24 Related articles How to Clean Your AR15 Bolt Carrier Group M4E1 Upper Receivers - Threaded vs Enhanced My firearm is not cycling properly. (AR15, M5, EPC) Ballistic Advantage Barrel Information What you will need after buying an AR15 Stripped Upper Receiver