Build a reliable and compact AR-15 platform with the Green Mountain 5.56 AR-15 Barrel 11.5″ M4 Finned Phosphate. This precision-crafted barrel delivers exceptional durability and performance for SBR or pistol configurations, featuring a distinctive finned M4 profile that enhances heat dissipation during sustained fire.
Key Features
- Chrome-lined bore and chamber for superior corrosion resistance and extended service life under demanding conditions.
- Phosphate finish provides a rugged, non-reflective surface that protects against rust and wear.
- Finned M4 profile combines classic aesthetics with improved thermal management for reduced heat buildup.
- 1:7 twist rate stabilizes a wide range of 5.56 NATO and .223 Remington loads, including heavier projectiles.
- Carbine-length gas system ensures reliable cycling with standard AR-15 components.
Technical Specifications
- Barrel Length: 11.5 inches
- Gas System: Carbine
- Gas Block Journal: 0.75 inches
- Muzzle Thread: 1/2×28
- Platform: AR-15 / M4 compatible
- Material: High-quality steel construction
- Finish: Phosphate with chrome lining
- Weight: 27.2 ounces
Benefits for Your Build
This barrel addresses common challenges in short-barreled AR builds by offering consistent reliability, reduced recoil impulse through proper gas tuning, and enhanced accuracy potential. The finned design helps maintain cooler operating temperatures, making it ideal for training, competition, or defensive applications where rapid follow-up shots are essential. Its mil-spec inspired dimensions ensure compatibility with a wide range of uppers, handguards, and gas blocks.
Whether you’re assembling a new project or upgrading an existing firearm, this Green Mountain barrel provides the balance of lightweight handling and robust construction that serious shooters demand.
Why Choose Green Mountain Barrels
Green Mountain is recognized for producing high-quality rifle barrels trusted by enthusiasts and professionals alike. Their attention to detail in rifling, chambering, and finishing results in components that deliver consistent performance without unnecessary complexity.


