Due to a process called Single Point Cut Rifling, these replacement barrels have an exact twist and a more uniform bore and groove. These barrels are pre-lapped before rifling and finish-lapped after rifling. This sage green .308 Win plain muzzle barrel is 20" in length and fits Accuracy International AT/AX short action rifles. Accuracy International .308 Win 20" Sage Green AT/AX Barrel 1420060GR