CMMG 55DE10A Barrel Sub-Assembly 5.56x45mm NATO 16.1\" M4 Profile Carbine Length

The CMMG 55DE10A Barrel Sub-Assembly is a drop-in 5.56x45mm NATO replacement barrel intended for assembling or rebuilding a custom AR-15 upper. Rather than a bare blank, it ships as a true sub-assembly with the M4 barrel extension already properly installed, so the builder drops it into the receiver, pins the gas system, and moves on to headspacing without an extra extension-fitting step. CMMG machines it from 4140 chromoly steel, cuts the classic M4 contour, and finishes the entire surface in a wear- and corrosion-resistant black nitride treatment.

At 16.10 inches overall and rifled with a fast 1:7 twist, this carbine-length barrel suits a wide range of AR-15 builds. The M4 feed ramp extension supports reliable feeding from a variety of magazine and ammunition combinations, and the carbine gas journal is positioned to work with standard carbine-length gas systems. The barrel ships with no iron sights installed, leaving the upper free for a flat-top receiver, a free-float handguard, and the optic or red dot of your choice.

The 55DE10A is equally at home as a build component for a feature-rich custom upper or as a direct replacement for a worn factory carbine barrel. Pair it with a quality low-profile gas block and your preferred AR-15 handguard, and the upper comes together quickly. This barrel sub-assembly brings the same build quality CMMG is known for across its complete rifles to the individual component buyer.