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 black .308 Win barrel is 24" in length with a 5/8x24 thread and fits Accuracy International AT/AX short action rifles. Accuracy International .308 Win 5/8"x24 24" AT/AX Barrel 1424062BL