The Diamondback Firearms 16-inch Mid-Length Barrel for 5.56x45mm (brand part no. 556M16M50B8R) gives AR-15 builders a duty-grade barrel from a company that also builds complete rifles and pistols, not just parts. Machined from 4150 chrome-moly vanadium steel and finished in black nitride for corrosion resistance, this medium-contour barrel runs a mid-length gas system for softer, more consistent cycling than a carbine-length setup. A 1:8 twist rate stabilizes a wide range of 5.56 bullet weights, and the button-rifled 5-groove bore, M4 feed ramps, and 11-degree target crown round out a barrel built for reliable feeding and consistent accuracy.

Key Specifications

• Chambered in 5.56x45mm NATO / .223 Rem.
• Measures 16 inches long with a mid-length gas system.
• Medium contour profile balances weight and rigidity.
• Machined from 4150 chrome-moly vanadium steel for durability under sustained fire.
• Finished in black nitride for corrosion resistance and a low-maintenance surface.
• 1:8 twist rate stabilizes a wide range of 5.56 bullet weights.
• Button-rifled, 5-groove bore for consistent accuracy.
• Threaded 1/2×28 at the muzzle for standard AR-15 muzzle devices.
• Cut with M4 feed ramps for reliable feeding.
• Finished with an 11-degree target crown to protect the bore’s accuracy at the muzzle.

Frequently Asked Questions

What gas system does this barrel use? A mid-length system, which tends to run softer and more consistently than a carbine-length setup.

What twist rate does it use? 1:8, which stabilizes a wide range of common 5.56 bullet weights.

Does it have M4 feed ramps? Yes, cut with M4 feed ramps for reliable feeding.

Buy the Diamondback Firearms 16in Mid-Length Barrel

Build on a barrel from a company that stakes its name on complete rifles. Order it from our Diamondback Firearms lineup, part of our AR barrels selection, at our Lubbock, Texas gun shop as soon as it’s ready to ship.