CMMG Barrel Sub-Assm 16.1inch MT 4140CM SBN 5.56mm

The CMMG Barrel Sub-Assembly 16.1-inch Medium Taper 4140 Chrome Moly 5.56mm is a precision-engineered upper receiver component purpose-built for custom AR15 upper assembly projects. This barrel sub-assembly arrives factory-headspaced with a properly installed M4 extension, eliminating guesswork and chambering variance on build day. The 5.56×45 NATO chamber and 1:7 twist rate provide optimal stability across standard-pressure ammunition, from 55-grain match rounds through heavier 77-grain loads commonly used in duty and long-range training environments.

Construction centers on 4140 chrome moly steel with salt bath nitride finish applied inside and out, delivering corrosion resistance critical for duty weapons exposed to moisture, salt spray, or extended storage. The medium taper profile balances weight savings against rigidity—a practical choice for carbine-length builds where 16.1-inch barrels support both precision and portability. Gas port specifications reflect midlength geometry with a .750-inch journal, tuning cyclic rate for reliable operation across buffer weights and spring combinations. The 1/2-28 muzzle threading accommodates standard AR suppressors, flash hiders, and compensators without adapter sleeves.

This barrel sub-assembly serves armed professionals, competitive shooters, and serious enthusiasts building duty-grade or recreational 5.56 carbines. The pre-assembled extension and factory headspace certification compress build time while eliminating a common point of failure. At 2.05 pounds, the component integrates seamlessly into SBR or standard carbine configurations. Buyers sourcing upper receiver components for law enforcement carbine builds, 3-gun competition, or precision rifle training benefit from CMMG's manufacturing standard and the verified headspace certification included with every unit.