Luth-AR 20in Fluted Bull Barrel AR-15 Build Kit with Adjustable Stock

The Luth-AR 20in Fluted Bull Barrel AR-15 Build Kit (brand part no. RKB203) puts almost everything a builder needs into one package, short of the stripped lower receiver itself. The kit centers on a fully assembled 20-inch fluted bull barrel upper fitted with a 15-inch vented KeyMod palm handguard, paired with a complete .223/5.56 lower parts kit and a choice of Magpul-pattern buttstock assembly, either the fixed MBA-1 or the adjustable MBA-3. Luth-AR designed this as a finish-the-build kit: a shooter supplies their own stripped lower, ideally a mil-spec unit, and everything else needed to complete a rifle is included in the box.

Key Specifications

• Includes a fully assembled 20-inch fluted bull barrel upper.
• Upper is fitted with a 15-inch vented KeyMod palm handguard.
• Includes a complete .223/5.56 lower parts kit.
• Choice of MBA-1 fixed or MBA-3 adjustable buttstock assembly.
• Does not include a stripped lower receiver; a mil-spec lower is recommended.

Frequently Asked Questions

Does this kit include a lower receiver? No, a stripped lower receiver is not included; Luth-AR recommends sourcing a mil-spec stripped lower separately.

What stock options come with this kit? A choice of the MBA-1 fixed rifle buttstock or the MBA-3 adjustable carbine buttstock.

What handguard is included? A 15-inch vented KeyMod palm handguard, already installed on the barreled upper.

Buy the Luth-AR 20in Fluted Bull Barrel AR-15 Build Kit

Finish your AR-15 build with nearly everything included but the lower. Order it from our Luth-AR lineup, part of our AR15 build kits selection, at our Lubbock, Texas gun shop for fast, direct shipping.