Green Mountain 5.56 AR-15 Barrel 16" M4 Crowned Phosphate - GM-M36

Upgrade your AR-15 build with the Green Mountain 5.56 AR-15 Barrel 16″ M4 Crowned Phosphate. Engineered for precision and durability, this carbine-length barrel delivers consistent performance for tactical, competition, and recreational shooters seeking a reliable 5.56 NATO option.

Key Features and Benefits

• Chrome-lined bore and chamber – Provides exceptional resistance to corrosion and wear, extending barrel life while maintaining accuracy through thousands of rounds.
• Phosphate exterior finish – Offers superior protection against rust and environmental factors, ensuring your barrel performs reliably in demanding conditions.
• M4 profile design – Balances weight and strength for improved handling without sacrificing rigidity or heat dissipation during sustained fire.
• 1:7 twist rate – Optimizes stabilization for a wide range of 5.56 NATO and .223 Remington bullet weights, enhancing accuracy and versatility.
• Carbine-length gas system with 0.75″ journal – Delivers smooth cycling and reliable operation in standard AR-15 configurations.
• Crowned muzzle – Ensures clean bullet exit for improved accuracy and reduced risk of damage during handling or transport.

Technical Specifications

• Caliber: 5.56 NATO
• Barrel Length: 16 inches
• Profile: M4
• Gas System: Carbine
• Twist Rate: 1:7
• Finish: Phosphate with chrome-lined bore and chamber
• Gas Block Journal: 0.75 inches
• Muzzle Threading: None
• Platform: AR-15
• Weight: 30.6 oz

Why Choose This Green Mountain Barrel?

Green Mountain barrels are manufactured to exacting standards using high-quality 4150 CMV steel, providing the toughness required for professional and enthusiast builds alike. The combination of chrome lining and phosphate coating addresses common pain points like fouling, corrosion, and maintenance, allowing you to focus on training and shooting rather than constant upkeep. Its M4 profile and carbine gas system make it an ideal drop-in upgrade for standard AR-15 uppers, delivering reliable feeding, extraction, and accuracy out of the box.

Whether you’re assembling a duty-ready rifle, a home defense platform, or a range plinker, this barrel offers the performance and longevity serious shooters demand.