Proof Research PR15 128657 16\" 6mm ARC Carbon Fiber AR-15 Barrel. This 16 inch AR-15 barrel features a match-grade 416R stainless steel core wrapped in aerospace-grade carbon fiber for enhanced performance. \n\n- Lightweight carbon fiber up to 64% lighter\n- Superior heat dissipation for sustained fire\n- Match-grade accuracy with 416R stainless core\n\nEngineered for AR-style rifles using Grendel Type II bolt, this PR15 barrel delivers strength, durability and precision in demanding conditions. It includes 1:7.5 twist rate, rifle-length gas system, .750 gas journal and 5/8-24 muzzle threading.