Faxon Firearms ARAK-21 7.62x39mm 16" Quad Rail w/ BCG & CH, Black - URSSB762

The ARAK-21 is a self-contained upper receiver assembly that brings gas-piston operation to your AR-15 platform. It's designed for easy, tool-free installation-simply attach it to your existing AR-15 lower receiver using the takedown and pivot pins, a process that takes less than a minute.This innovative upper receiver boasts a Barrel Assembly Unit (BAU), which includes the barrel, gas block, muzzle brake, gas piston, gas adjuster, and barrel trunnion. The gas adjuster knob is the only removable component of the BAU, offering four settings: three for optimal gas flow under different conditions and one for single-shot operation.The ARAK-21 upper receiver also comes equipped with a charging block, standard charging handle, lower forearm with screws, three full-length aluminum Picatinny rails, three insulating shims, a bolt carrier assembly, a lower recoil lug with a spring guide rod, and a dual recoil spring system.Due to its unique design, the ARAK-21 has minimal parts interchangeability with a standard AR-15. Only the firing pin, extractor spring, and ejector spring are standard and can be swapped with AR-15 components.