The FN AR-15 5.56mm 14.5-Inch Replacement Barrel (brand part number 36420) brings genuine FN America manufacturing quality to a factory-spec AR-15 barrel swap. Chambered in .223 Remington/5.56 NATO, this barrel is built to the same standards FN uses on its military and law enforcement contracts, giving builders and gunsmiths a reliable, accurate replacement for a worn or damaged upper. It’s sold as a bare barrel only, with no receiver included.

Key Specifications

• Chambered in .223 Remington/5.56 NATO for broad ammunition compatibility.
• Measures 14.5 inches in barrel length.
• Cut with a 1 in 7-inch right-hand twist, stabilizing the full range of common 5.56 bullet weights.
• Machined from cold hammer-forged chrome moly vanadium steel, the same barrel steel FN uses on its machine gun barrels.
• Bore and chamber are chrome-lined for corrosion resistance and extended barrel life under sustained fire.
• Built around a carbine-length gas system.
• Finished in a matte black manganese phosphate coating for corrosion resistance.
• Cut with M4-style feed ramps for consistent, reliable feeding.
• Threaded 1/2×28 at the muzzle to accept standard AR-15 muzzle devices.
• Sold as a bare AR-15 replacement barrel, with no bolt carrier group or upper receiver included.

Frequently Asked Questions

What twist rate does this barrel use? It’s cut with a 1 in 7-inch right-hand twist, which reliably stabilizes both light and heavy 5.56/.223 bullet weights.

Is this barrel legal to buy and own on its own? Yes, a bare 14.5-inch barrel is an ordinary Title I part. Federal law only restricts how it can be installed — pairing a barrel under 16 inches with a shouldered rifle-configured lower without proper registration would create an unregistered short-barreled rifle, so installation should be limited to a pistol-configured build or a properly registered SBR lower.

Does this barrel come with a bolt carrier group? No, this listing is for the barrel only; a bolt carrier group and upper receiver are needed separately to complete an upper assembly.

Buy the FN AR-15 5.56mm 14.5-Inch Replacement Barrel

Rebuild your upper with the same barrel quality FN supplies to military and law enforcement customers. Order the FN America barrel from our AR barrels selection, shipped fast from our Lubbock, Texas gun shop.