CMMG MK4 Upper Receiver Assembly .223 Rem/5.56 NATO 14.5" Forward Assist

The CMMG MK4 is a complete AR-15 upper receiver assembly chambered in .223 Rem/5.56 NATO, built around a 14.5" steel barrel with matte black finish. The barrel features a 1:7" twist rate optimized for heavier projectiles and utilizes a carbine-length gas system for reliable cycling. This upper receiver assembly includes a forward assist mechanism for enhanced functionality. The steel construction ensures durability while the matte black finish provides corrosion resistance and tactical appearance.