Upgrade your AR-15 build with the Green Mountain 5.56 AR-15 Barrel 20" M16 A1 Phosphate, a precision-engineered component designed for shooters who demand accuracy, durability, and authentic M16-style performance. Crafted to exacting standards, this barrel delivers reliable function in both recreational and tactical applications while supporting modern 5.56 NATO ammunition. Key Features and Benefits Chrome-lined bore and chamber with phosphate exterior finish - Provides exceptional corrosion resistance and extended service life, reducing maintenance needs and ensuring consistent performance in varied conditions. Government / SOCOM profile with rifle-length gas system - Offers a balanced weight distribution for improved handling and reduced recoil, ideal for precision shooting or duty use. 0.625" gas block journal and 1/2x28 muzzle threads - Ensures compatibility with standard low-profile gas blocks and a variety of muzzle devices for custom configurations. M16-style extension and 20-inch length - Delivers classic ergonomics and velocity for effective terminal performance at longer ranges. Technical Specifications Platform: AR-15 Caliber: 5.56 NATO Barrel Length: 20 inches Twist Rate: 1:12 Gas System: Rifle length Gas Block Journal: 0.625 inches Muzzle Thread: 1/2x28 Finish: Phosphate with chrome-lined bore and chamber Barrel Profile: Government / SOCOM Weight: 35.4 ounces Why Choose This Product This barrel addresses common pain points for AR-15 builders, such as inconsistent accuracy with varying ammunition and premature wear in harsh environments. The robust construction from premium materials ensures tight tolerances for reliable feeding, extraction, and grouping. Whether restoring a classic M16A1 replica or building a modern tactical rifle, it provides the foundation for dependable operation without compromising on quality or compatibility. Invest in a barrel that combines proven design with contemporary performance enhancements for years of trusted service.