Experience reliable performance and precision in your AR-15 build with the Green Mountain 5.56 AR-15 Barrel 12.7″ M4 A1 Phosphate. Designed for tactical enthusiasts and builders seeking a compact, durable option, this barrel delivers consistent accuracy and smooth operation in demanding conditions.
Key Features
- Chrome-lined bore and chamber for enhanced durability, reduced fouling, and extended service life even with high-volume shooting.
- M4 profile construction provides a lightweight yet robust design that maintains balance without sacrificing strength.
- 1:7 twist rate stabilizes a wide range of bullet weights, including heavier projectiles for improved long-range accuracy.
- Phosphate finish offers superior corrosion resistance and a low-maintenance exterior that withstands harsh environments.
- Carbine-length gas system ensures reliable cycling with standard AR-15 components and various ammunition types.
Specifications
- Barrel Length: 12.5″ (overall 12.7″)
- Caliber: 5.56 NATO
- Twist Rate: 1:7
- Gas System: Carbine
- Gas Block Journal: 0.75″
- Muzzle Thread: 1/2×28
- Finish: Phosphate with chrome-lined bore and chamber
- Material: 4150 chrome moly vanadium steel
- Barrel Profile: M4
- Weight: 26.4 oz
Benefits for Your Build
This barrel addresses common challenges in short-barreled AR-15 configurations by combining maneuverability with reliable function. The chrome lining minimizes wear from rapid fire, while the 1:7 twist supports versatile ammunition choices. Its M4 contour keeps weight down for faster handling in dynamic scenarios, making it ideal for home defense, competition, or tactical applications.
Why Choose This Green Mountain Barrel
Green Mountain Rifle Barrels are trusted by OEM manufacturers for their consistent quality and precision manufacturing. This model integrates seamlessly into standard AR-15 platforms, offering mil-spec features at an accessible level without compromising on performance or longevity.
Upgrade your next build with this versatile 5.56 AR-15 barrel and enjoy dependable accuracy and durability that meets the needs of serious shooters.

