The AR-10® .308 Win 16” A4 Carbine Barrel Assembly is a complete assembly including a MIL-STD 1913 rail gas block, barrel nut, slip ring, slip ring spring, slip ring retaining ring, gas tube, and handguard cap. Constructed from Chrome Moly, the bore is Chrome lined, with M-4 feed ramps. Coated in a durable phosphate finish. Thread 5/8×24 with .750” gas block journal.