5.56 NATO Rifles, Pistols & Uppers5.56 NATO is the caliber that defines the AR-15 platform. Every Radical Firearms rifle, pistol, and upper chambered in 5.56 runs a button-rifled 4150 chromoly vanadium (CMV) barrel, nitride-treated bolt carrier, and forged 7075-T6 upper receiver — the same spec the M4 carbine is built to. Whether you’re finishing a home-defense carbine, a 3-gun competition rifle, or a short-barrel pistol, the 5.56 lineup delivers mil-spec reliability at manufacturer-direct pricing.What 5.56 gives youCheap factory ammo (under $0.40 per round for brass-case), flat trajectory to 400 yards with 62gr bullets, low felt recoil, and the widest AR accessory ecosystem of any caliber. The .223 Wylde chamber (included on our stainless match uppers) also shoots .223 Remington safely — no compromise either direction.Related CategoriesAR-15 RiflesAR-15 PistolsAR-15 Uppers5.56 AmmoSuppressorsEvery firearm on this page ships direct from our Stafford, Texas facility to the transferring FFL dealer of your choice. California, New York, New Jersey, and Massachusetts-compliant configurations available on request. NFA items (suppressors, SBRs) require Form 4 processing through your transferring dealer.