Cmc barrels ar-15 barrel was designed to be the perfect addition to any new or current rifle build.Made from 4150 chrome moly vanadium, socom barrel profile, coated in h&m blacknitride+ for increased wear resistance, chambered in.223 wylde so that you can feed it both.223 and 5.56 nato ammo.Featuring m4 feed ramps for reliability; 11-degree match crown for increased accuracy; bottom dimple for easy gas block install and alignment; socom barrel profile; mid length gas system; air gauged.Gas block diameter:.750" with a gas block journal length of 1.13".Length: 16.25"Model: AR BarrelsTwist: 1:7"Finish: Black NitrideBarrel Type: Button RifledAmmo Type: Centerfire