These amazing cold hammer forged barrels are extremely durable with a 20,000+ round service life. These lightweight 14.5″ barrels weigh 22.0 oz with M4 barrel extension and no front sight base. The barrels have a .750″ gas block seat with a properly sized gas port, and the muzzle is threaded perfectly concentric to the bore with 1/2×28 threads. These barrels are made to military specifications for the M249 SAW. The cold hammer forging process work-hardens the steel around a rifled mandrel, which creates the lands and grooves. These barrels are chambered in 5.56 NATO, with a 1:7 twist rate. The barrel blanks are the correct certified CMV material and they are also hard chrome lined to the M249 SAW MIL-SPEC, which is almost twice as thick as the hard chrome on a MIL-SPEC M4. The result is a rifle that can be run hard day after day! Each barrel is high pressure tested and magnetic particle inspected. They have M4 barrel extensions, and are phosphate finished on the outside (under the front sight base as well).