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. These barrels feature AI's proprietary medium Palma type contour that is new for 2018. These barrels are compatible with Accuracy International's AT and AX weapon systems. Accuracy International AT/AX Black .308 Win 24" 5/8"-24 w/cap 2018 Profile Barrel 1424082BL