CMMG 55DC70A AR-15 Barrel Sub-Assembly 5.56 NATO
CMMG 16.1" 5.56 NATO barrel sub-assembly with M4 extension, 4140 chromoly steel, nitride finish, midlength gas system, and 1:7 twist rate for AR-15 builds.
Fits: AR-15
CMMG 55DC70A Barrel Sub-Assembly
This complete barrel sub-assembly from CMMG provides everything you need for a quality AR-15 upper receiver build. The barrel arrives with the M4 extension properly installed and headspaced, eliminating guesswork during assembly.
Key Specifications
- Caliber: 5.56×45 NATO
- Barrel Length: 16.1 inches
- Material: 4140 chromoly steel
- Finish: Salt bath nitride (inside and out)
- Twist Rate: 1:7
- Gas System: Midlength
- Gas Journal Diameter: .750 inch
- Muzzle Thread: 1/2-28
- Profile: Medium taper
Why Choose This Barrel
The 16.1-inch midlength configuration strikes an excellent balance between velocity and handling. The 1:7 twist rate stabilizes a wide range of bullet weights, from lightweight 55-grain rounds to heavier 77-grain match ammunition. The nitride finish provides superior corrosion resistance and durability compared to standard parkerizing.
CMMG's attention to detail—including proper headspacing and extension installation—means you can focus on the rest of your build with confidence. This is a no-compromise component for serious AR-15 builders.
