The AR57 ULT 12in Barrel 5.7x28mm Upper Receiver Assembly can be used with PS-90 magazines, however, the best mags to use with this upper are AR57 brand P90 pattern mags …

AR57 12" Complete ULT M-LOK Upper, AR57 Mfg, Factory new. Comes with a 12" lightweight barrel with M-LOK rails. This AR57 Upper Receiver Assembly converts any AR-15 lower to a …

The AR57 ULT Complete Upper Assembly, chambered in 5.7x28mm with a 12" lightweight barrel and M-LOK rails transforms any AR-15 lower into a 5.7x28 firearm. Featuring a unique top …

This upper receiver is chambered in 5.7x28mm and features a steel 12" lightweight barrel with 1:8.5" twist and a 1/2x28 thread pattern. This AR57 Upper is constructed with a steel barrel, …

Experience the ballistic performance of the iconic FN P90 in the familiar AR-15 platform with a 5.7x28 upper receiver from Classic Firearms. Whether you're looking for a rifle or pistol upper, …

This cutting-edge AR57 Upper seamlessly integrates into any standard lower, ensuring you experience smooth, hassle-free installation and use. Delving into the specifics, the unit boasts …

Comes with a 12″ lightweight barrel with M-LOK rails. This AR57 Upper Receiver Assembly converts any AR-15 lower to a rifle capable of shooting 5.7×28 ammunition. The unique upper …

Comes with a 12" lightweight barrel with M-LOK rails. This AR57 Upper Receiver Assembly converts any AR-15 lower to a rifle capable of shooting 5.7×28 ammunition. The unique upper …