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 .338 Norma Magnum barrel is 27" in length, has a M18x1.5 thread and fits Accuracy International AXMC rifles. Accuracy International AXMC Black .338 Norma Mag 27" M18x1.5 2018 Profile Barrel 1827071BL