Criterion Barrels Hybrid AR-15 Barrel 223 Wylde 13.9 Mid-Length Chrome-Lined 1:8 Twist Black. Hybrid contour mid-weight AR-15 barrel optimized for balanced weight, heat absorption, and harmonics. 13.9 inch mid-length gas system, chrome-lined bore, 1:8 twist, finished in black. Designed for AR-15 platforms with Wylde chambering suitable for 5.56x45mm and .223 Remington ammunition. Headspace and chambering should be verified for reliable performance.