
Availability: In Stock
The CMMG 12.5" Multi-Role .223 Rem barrel sub-assembly is a complete, ready-to-install solution for AR-15 upper builds where compact profile and versatility matter. Whether you're assembling a short-range patrol rifle, a home-defense upper, or a truck gun, this barrel strikes the balance between maneuverability and controllable performance. It arrives properly headspaced with the M4 extension already installed—no gunsmithing required—so you can focus on the rest of your build.
Built from 4140 chrome moly steel and finished inside and out with salt bath nitride, this barrel resists corrosion and handles hard use without complaint. The multi-role profile keeps weight down while maintaining enough mass for consistent accuracy at practical distances. The 1:7 twist stabilizes a wide range of .223 and 5.56 NATO loads, making it genuinely flexible if you plan to experiment with different ammunition or bullet weights. Carbine-length gas system gives you a reliable, time-tested dwell curve for 12.5" barrels—expect smooth cycling and predictable reliability whether you're running standard or heavy ammunition.
The 1/2-28 threaded muzzle accepts suppressors, brakes, or flash hiders without adaptation. If you're planning a dedicated short-barrel build—a truck gun, a home-defense rifle, or a compact duty upper—this barrel handles the role without compromise. Pair it with your receiver set, handguard, and bolt carrier group to complete a working upper.
| Barrel Length | 12.5 inches |
| Caliber | .223 Rem / 5.56x45 NATO |
| Profile | Multi-Role |
| Material | 4140 Chrome Moly Steel |
| Finish | Salt Bath Nitride (inside and out) |
| Twist Rate | 1:7 |
| Muzzle Thread | 1/2-28 |
| Gas Port | Carbine Length |
| Gas Journal Diameter | .750 inch |
| Barrel Extension | M4 (pre-installed) |
This is a barrel sub-assembly only. You'll need a receiver set, handguard, bolt carrier group, and charging handle to complete a functioning upper. The barrel arrives with the extension installed and headspaced, so assembly is straightforward for anyone comfortable with basic AR-15 builds.
Yes. CMMG headspaces all barrel sub-assemblies at the factory, so you don't need to have it done by a gunsmith before installation.
Yes. The 1/2-28 threaded muzzle accepts standard .223/5.56 suppressors, as well as muzzle brakes, flash hiders, and other threaded devices.
The 1:7 twist is a general-purpose rate that stabilizes a wide range of .223 Remington and 5.56x45 NATO ammunition, from standard 55-grain loads up through heavier projectiles—giving you flexibility to use what you have on hand.

SKU: 115788971 • Weight: 2.25oz





Availability: In Stock
The CMMG 12.5" Multi-Role .223 Rem barrel sub-assembly is a complete, ready-to-install solution for AR-15 upper builds where compact profile and versatility matter. Whether you're assembling a short-range patrol rifle, a home-defense upper, or a truck gun, this barrel strikes the balance between maneuverability and controllable performance. It arrives properly headspaced with the M4 extension already installed—no gunsmithing required—so you can focus on the rest of your build.
Built from 4140 chrome moly steel and finished inside and out with salt bath nitride, this barrel resists corrosion and handles hard use without complaint. The multi-role profile keeps weight down while maintaining enough mass for consistent accuracy at practical distances. The 1:7 twist stabilizes a wide range of .223 and 5.56 NATO loads, making it genuinely flexible if you plan to experiment with different ammunition or bullet weights. Carbine-length gas system gives you a reliable, time-tested dwell curve for 12.5" barrels—expect smooth cycling and predictable reliability whether you're running standard or heavy ammunition.
The 1/2-28 threaded muzzle accepts suppressors, brakes, or flash hiders without adaptation. If you're planning a dedicated short-barrel build—a truck gun, a home-defense rifle, or a compact duty upper—this barrel handles the role without compromise. Pair it with your receiver set, handguard, and bolt carrier group to complete a working upper.
| Barrel Length | 12.5 inches |
| Caliber | .223 Rem / 5.56x45 NATO |
| Profile | Multi-Role |
| Material | 4140 Chrome Moly Steel |
| Finish | Salt Bath Nitride (inside and out) |
| Twist Rate | 1:7 |
| Muzzle Thread | 1/2-28 |
| Gas Port | Carbine Length |
| Gas Journal Diameter | .750 inch |
| Barrel Extension | M4 (pre-installed) |
This is a barrel sub-assembly only. You'll need a receiver set, handguard, bolt carrier group, and charging handle to complete a functioning upper. The barrel arrives with the extension installed and headspaced, so assembly is straightforward for anyone comfortable with basic AR-15 builds.
Yes. CMMG headspaces all barrel sub-assemblies at the factory, so you don't need to have it done by a gunsmith before installation.
Yes. The 1/2-28 threaded muzzle accepts standard .223/5.56 suppressors, as well as muzzle brakes, flash hiders, and other threaded devices.
The 1:7 twist is a general-purpose rate that stabilizes a wide range of .223 Remington and 5.56x45 NATO ammunition, from standard 55-grain loads up through heavier projectiles—giving you flexibility to use what you have on hand.
SKU: 115788971 • Weight: 2.25oz
