The base barrel configuration needed for a fast handling, lightweight barrel. Brownells Lightweight Carbine Barrels come in a variety of popular lengths, ready to suite any new carbine build. Manufactured to Brownells specifications by Rosco Manufacturing, the button rifled barrels, profiled from 4150 Chrome Moly Vanadium steel, feature a 223 Wylde chamber, that allows them to accommodate 223 Remington and 5.56x45mm NATO ammunition equally well.The 1-8 twist will handle commonly available Full Metal Jacket 55gr loads, all the way up to heavier, premium 77gr bullets.All of these Lightweight Barrels have a .625 gas block journal to correspond with the overall slim profile, preventing your C Mfg: Brownells