5.7×28mm Platform · Est. 2003
AR FIVE- SEVEN
The future of design. Engineered for the modern enthusiast — top-mounted, free-floating, 50-round capacity. Unlike anything else in its class.
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The future of design. Engineered for the modern enthusiast — top-mounted, free-floating, 50-round capacity. Unlike anything else in its class.
The AR Five Seven combines a top-mounted upper receiver, free-floating barrel, and 5.7×28mm NATO cartridge into a lightweight, high-capacity platform unlike anything else on the market.
Top-mounted upper ejects casings forward, keeping the action clean. Field-strips faster than any comparable platform.
Free-floating barrel eliminates harmonic interference. Sub-MOA capable under rapid fire in adverse field conditions.
Just over six pounds complete. Full M-LOK rail coverage accepts every modern optic, light, and accessory.
Every component machined to AR Five Seven specification. Available direct — contact us to place your order.
AR57 12" Complete ULT M-LOK Upper — factory new. Converts any AR-15 lower to shoot 5.7×28mm. Kryptonite Monobloc 7075-T6 aluminum receiver, melonite finish, M-LOK rails. Includes one 50-round magazine.
⚠ Complete upper receiver assembly. Drop-in ready — push pin installation.
AR57 16" Complete ULT M-LOK Upper — factory new. 16" barrel with perforated muzzle brake on ½×28 threads; 18" overall barrel length. Converts any AR-15 lower to shoot 5.7×28mm. 8620 alloy bolt, melonite finish. Includes one 50-round magazine.
⚠ Complete upper receiver assembly. Drop-in ready — push pin installation.
Full bolt assembly. Drop-in ready, precision-fit to AR Five Seven specification.
⚠ This is for the Bolt Only.
Integrated magazine release. Standard M-LOK accessory compatibility.
⚠ This is for the Rear Rail Assembly only.
Twenty years building the most capable 5.7mm platform on the market. No compromises.
The AR Five Seven was engineered from the ground up around the FN 5.7×28mm cartridge — a high-velocity, low-recoil round originally designed to defeat soft body armor. Our top-mounted upper keeps the profile low while the free-floating barrel delivers military-grade precision from a civilian build. Over 100,000 barrels sold. Over 45 industry awards. Built in the USA.
Full technical documentation — assembly, disassembly, maintenance procedures, exploded parts diagrams, and specifications. Flip through every page below.
Ready to order parts or need technical support? Our team responds within 24 hours.