The Ballistic Advantage BABL556020M Modern Series 5.56x45mm NATO 18" Black QPQ Finish 4150 Chrome Moly Vanadium Steel Material Rifle Length SPR Profile with OPS 12 for AR-15 delivers a precision-ground option for AR-15 builders seeking reliable performance and stability in a rifle-length platform. Crafted from 4150 Chrome Moly Vanadium steel and finished in a rugged Black QPQ treatment, this 18-inch barrel features a 1:7 twist rate designed to stabilize a broad range of 55 to 77 grain projectiles, making it well suited for tactical applications, varmint hunting, and target shooting. The SPR profile with OPS 12 optimizes weight distribution and reduces muzzle rise, promoting smoother follow-up shots and consistent accuracy across extended strings of fire. Ballistic Advantages Modern Series barrels are engineered for longevity and consistent bore quality, ensuring dependable chamber integrity and repeatable performance in dynamic field conditions. Whether upgrading an existing AR-15 build or assembling a high-performance rifle for competition or enterprise use, this 18" barrel pairs seamlessly with compatible receivers to deliver ballistic efficiency, enhanced heat management, and a clean, finished aesthetic that complements a wide range of configurations.