The Criterion AR-15 Hybrid barrel is designed for extreme accuracy without the added weight that a typical HBAR contour has. These barrels are chambered in .223 Wylde with a 1:8 button rifled twist rate to squeeze out every bit of accuracy possible. The chrome lining process makes the bore extremely hard to withstand the constant friction of a high-powered round passing through resulting in a long barrel life. The bore is then hand-lapped to make sure the lands and grooves are as smooth and consistent as possible to further ensure you are getting the most accuracy as possible. This 10.5 inch barrel is built with a carbine length gas system and an optimized gas port size to ensure reliable function with both 5.56 and .223 ammunition.