Faxon Firearms ARAK-21 16" 5.56 NATO Complete Upper

The Faxon ARAK-21 is a long-stroke gas piston upper that drops onto any standard AR-15 lower, blending the AR ergonomic shell with an AK-style operating system. Instead of routing gas back into the receiver like a direct-impingement AR, the ARAK-21 runs a long-stroke piston and op-rod carrier that keeps fouling and heat out of the action. The op-rod carrier reciprocates inside the receiver, but the forward-mounted side charging handle stays put while the gun cycles, so there is no rear charging handle slot and the optic rail stays clear front to back.

The charging handle is fully ambidextrous and can be swapped to either side of the upper, and ejection is independently selectable left or right. That combination makes the ARAK-21 one of the few uppers that a left-handed shooter can run without a single right-handed compromise: charge on the left, eject to the left, and never break the firing grip. The 5-position adjustable gas regulator is the other half of the appeal. Three cycling positions let shooters tune the gas for standard or adverse-condition reliability, a dedicated suppressed setting cuts back-pressure and gas-to-face, and a single-shot setting closes the gas entirely for manual operation.

The 16-inch 5.56 NATO barrel is threaded 1/2x28 for standard AR-15 muzzle devices and 5.56-rated suppressors, and the aluminum free-float handguard carries a full-length Picatinny rail up top for optics and backup sights. Because the entire system mounts to a mil-spec lower, the only build decisions left are the lower, a muzzle device or can, and an optic. For shooters who want a tunable, ambidextrous, piston-driven side charger, the ARAK-21 is the most complete drop-in path.