Green Mountain 5.56 AR-15 Barrel 18" M4 Passivated - GM-M24-556

Upgrade your AR-15 build with the precision-engineered Green Mountain 5.56 AR-15 Barrel 18″ M4 Passivated. Designed for reliability and accuracy in tactical and recreational applications, this stainless steel barrel delivers consistent performance for shooters seeking a balanced rifle-length option.

Key Features

• M4 profile provides a lightweight yet durable construction ideal for extended use without excessive weight
• Passivated stainless finish enhances corrosion resistance for long-term durability in various environments
• 1:8 twist rate stabilizes a wide range of bullet weights from 55gr to 77gr for versatile ammunition compatibility
• Rifle-length gas system promotes smooth cycling and reduced recoil for improved shooter control
• 5.56 NATO chamber ensures reliable feeding and extraction with both military and commercial loads

Specifications

• Barrel Length: 18 inches
• Barrel Profile: M4
• Finish: Passivated Stainless
• Platform: AR-15
• Cartridge: 5.56 NATO
• Twist Rate: 1:8
• Gas System: Rifle length
• Gas Block Journal: 0.75 inches
• Muzzle Thread: 1/2×28
• Weight: 34.8 oz

Benefits for AR-15 Builders

This barrel addresses common pain points like accuracy inconsistencies and maintenance challenges. The M4 contour balances maneuverability with heat dissipation, while the passivated surface simplifies cleaning and resists wear. With a 1:8 twist optimized for modern loads, it supports precision shooting at distance without compromising close-range performance. The rifle gas system reduces bolt carrier velocity for smoother operation and extended component life.

Why Choose Green Mountain Barrels

Green Mountain manufactures barrels with a focus on quality materials and tight tolerances, making them a trusted choice among custom builders. The 18″ length offers an excellent compromise between velocity and handling for mid-range engagements.

Common Questions

What bullet weights work best with the 1:8 twist? This twist rate effectively stabilizes projectiles from 55 to 77 grains, providing flexibility for target shooting, varmint control, and tactical scenarios.

Is this barrel compatible with standard AR-15 uppers? Yes, it features an M4 extension and standard threading for seamless integration with most AR-15 platforms.

How does the passivated finish benefit maintenance? Passivation creates a protective layer on the stainless steel, reducing oxidation and making the barrel easier to clean while maintaining its appearance over time.

Build a reliable, accurate rifle with this Green Mountain barrel—ideal for enthusiasts prioritizing performance and longevity in their AR-15 platform.