The Luth-AR Fluted Bull Barrel Rifle Kit (brand part number RKB201) builds a full-length precision-oriented AR-15 around a 20-inch fluted bull barrel, leaving only the stripped lower receiver for the builder to source. Built by Luth-AR, the .223 Remington barrel is machined from 416 stainless steel with a 1:9 right-hand twist and button-broached rifling, threaded 1/2×28 and fitted with an A2 flash hider. The kit ships as a fully assembled upper with a 15-inch vented KeyMod palm handguard, a complete lower parts kit, and this configuration is set up with a fixed MBA-1 buttstock assembly, though Luth-AR’s adjustable MBA-3 stock remains available as an alternate option.

Key Specifications

• Barrel length is 20 inches, with a fluted bull contour for weight reduction.
• Barrel material is 416 stainless steel with button-broached rifling.
• Twist rate is 1:9 right-hand, threaded 1/2×28.
• Handguard is a 15-inch vented KeyMod palm handguard.
• Includes a complete lower parts kit for finishing the build.
• Configured with a fixed MBA-1 rifle buttstock assembly.

Frequently Asked Questions

Why choose the 20-inch barrel over the 16-inch version? The longer barrel and fixed rifle stock suit precision and long-range shooting better than the shorter carbine-length kit.

Is the lower receiver included? No, this kit does not include a lower receiver; Luth-AR recommends sourcing a Mil-Spec stripped lower separately.

Buy the Luth-AR 20-inch Fluted Bull Barrel Rifle Kit

Build a precision-oriented AR-15 around a lightweight fluted bull barrel. Order this AR-15 build kit from our Lubbock, Texas gun shop for fast, insured shipping to your door.