The Radian Weapons AX556 Builder Kit (Radian part no. R0437) is a matched complete upper and lower receiver set built around Radian’s Model 1 design philosophy of premium raw materials and precise CNC machining, finished in Brown for this 8.5-inch configuration. Every AX556 set is assembled by hand by a trained gunsmith who inspects, test-fires, and cleans the rifle before it ships, and the design carries fully ambidextrous controls so left- and right-handed shooters get equal utility from the same platform. This compact 8.5-inch configuration gives builders a pistol-length receiver set ready for the rest of a custom build.

Key Specifications

• Multi-caliber compatible lower/upper receiver set, not a bare single component.
• 8.5-inch configuration suited to a compact, pistol-length build.
• Fully ambidextrous controls give equal utility to left- and right-handed shooters.
• Each set is hand-assembled, test-fired, and cleaned by a trained gunsmith before shipping.
• Semi-automatic fire control group ships installed and ready to complete.
• Finished in Brown for a distinctive, field-ready appearance.
• Backed by Radian’s lifetime guarantee on every Model 1 receiver set.
• Runs a Raptor-SD ambidextrous charging handle.
• Equipped with a Talon ambidextrous safety selector.

Frequently Asked Questions

Does this kit include both the upper and lower receiver? Yes, it is a matched receiver set covering both halves of the rifle, not a single component.

Are the controls ambidextrous? Yes, Radian builds full ambidextrous controls into every AX556 for equal left- and right-hand use.

Is this set backed by a warranty? Yes, every Radian Model 1 receiver set carries a lifetime guarantee.

Buy the Radian Weapons AX556 Builder Kit Complete Upper/Lower Set 8.5-inch Brown

Order the Radian AX556 Builder Kit from our Radian Weapons lineup of AR15 uppers for fast, insured shipping to your FFL from our Lubbock, Texas gun shop.