Criterion Barrels Fluted AR-15 Barrel in 223 Wylde, 20 Rifle-Length, 1:8 twist, stainless steel. Fluted design with eight flutes around the gas block journal reduces weight while maintaining rigidity. Proper headspace should be checked for reliable performance. This barrel is designed for AR-15 platforms in 223 Wylde chambering, suitable for rifles using standard operating gas systems.