Green Mountain 9mm AR-15 Barrel 16" M4 Nitride - GM-M21

Engineered for precision and reliability in 9mm AR-15 platforms, the Green Mountain 16″ M4 Nitride barrel delivers exceptional performance for tactical and recreational shooters. This blowback-operated barrel combines a proven M4 contour with advanced nitride finishing to provide the durability and accuracy demanded in modern firearm builds.

Key Features

• 16-inch barrel length optimized for balanced velocity and handling in 9mm AR-15 configurations
• M4 profile offers a lightweight yet robust design that reduces overall firearm weight without sacrificing strength
• Nitride/Melonite finish provides superior corrosion resistance and a smooth, low-maintenance surface
• 1:10 twist rate ensures stable projectile flight for a wide range of 9mm ammunition
• 1/2×36 muzzle thread pattern accommodates popular muzzle devices and compensators
• Blowback gas system designed specifically for reliable 9x19mm operation

Specifications

• Platform: AR-15
• Cartridge Compatibility: 9x19mm / 9mm
• Barrel Length: 16 inches
• Barrel Profile: M4
• Finish: Nitride / Melonite
• Twist Rate: 1:10
• Muzzle Thread: 1/2×36
• Gas System: Blowback (no gas block journal required)
• Weight: 28 oz
• Material: Precision-machined steel (consistent with Green Mountain’s 41V50 standards)

Why Choose This Product

Green Mountain Rifle Barrel Company has built a reputation for manufacturing high-quality barrels that deliver consistent accuracy and long service life. This 9mm-specific model addresses common challenges in pistol-caliber AR builds, including reliable feeding, reduced fouling, and enhanced corrosion protection in varied environments. The nitride treatment extends barrel life while simplifying cleaning, making it an ideal choice for high-volume shooters and those seeking a dependable upgrade for their AR-15 9mm project.

Whether you’re assembling a home-defense carbine or a competition-ready platform, this barrel provides the foundation for smooth operation and repeatable accuracy. Its specifications align perfectly with standard 9mm blowback uppers, ensuring seamless integration into your existing build.

Invest in proven craftsmanship from a trusted American manufacturer and experience the difference precision engineering makes in your next range session or tactical application.