The Faxon Firearms Duty Series AR-15 5.56 NATO 1:8 4150 CMV Barrel is built for reliable accuracy and durability in duty, defense, or competitive shooting applications. Machined from 4150 Chrome Moly Vanadium steel with a QPQ Nitride finish for exceptional corrosion resistance, this barrel is button rifled with a 1:8 twist to stabilize a wide range of 5.56 NATO loads. This barrel also features 1/2x28 threads for compatibility with a variety of muzzle devices, including flash hiders, brakes, and suppressor mounts. Plus, an 11° target crown enhances accuracy, while magnetic particle inspection (MPI) ensures material integrity and reliability under sustained use. Compatible with most Mil-Spec AR-15 platforms. M4 barrel extension.