The LMT Monolithic 5.56×45 NATO 20” Rifle-Length Barrel in Black (LMT part no. R-L7RA1B) is a factory-spec barrel built for LMT’s MRP monolithic upper receiver platform, giving shooters the full 20-inch rifle-length configuration for maximum velocity and long-range accuracy from a 5.56 NATO AR15. The rifle-length gas system paired with this barrel length produces a smooth, low-recoil cycling impulse well suited to precision and service-rifle-style shooting. The 1-in-7 twist stabilizes heavier 5.56 NATO bullets favored for longer-range work. LMT builds this barrel to the same spec used on its complete rifles.

Key Specifications

• Measures 20 inches long, maximizing velocity and range from 5.56 NATO ammunition.
• Chambered in 5.56×45 NATO, the standard AR15 platform cartridge.
• Rifled with a 1-in-7 twist, stabilizing heavier NATO-spec 5.56 bullets.
• Built for the LMT MRP monolithic upper platform, and finished in black.
• Paired with a rifle-length gas system for maximum velocity and a smooth cycling impulse.
• Compatible with LMT’s MRP monolithic upper receiver platform.
• Uses a standard barrel extension compatible with mil-spec 5.56 bolt carrier groups.

Frequently Asked Questions

Why choose a 20-inch barrel over a shorter carbine length? A 20-inch barrel with a rifle-length gas system generally delivers higher velocity, better long-range accuracy, and softer recoil impulse than shorter configurations.

Does this barrel fit LMT’s own upper receivers? Yes, it’s built to mate with the LMT MRP monolithic upper receiver system.

Buy the LMT Monolithic 5.56 NATO 20-inch Rifle-Length Barrel, Black

Order the LMT Defense 20-inch barrel from our AR barrels selection, shipped fast and insured from our Lubbock, Texas gun shop.