Panzer Arms AR57 Ultra Light Tactical 5.7x28mm Upper is a complete upper receiver that converts any mil-spec AR-15 lower to shoot 5.7x28mm ammunition. This alloy monobloc …

This AR57 Upper Receiver Assembly converts any AR-15 lower to a rifle capable of shooting 5.7×28 ammunition. The unique upper design loads from the top and ejects downward through …

This upper receiver is chambered in 5.7x28mm and features a steel 16" barrel with 1:8.5" twist and a 1/2x28 thread pattern. This AR57 Upper is constructed with a steel barrel, muzzle brake, …

Convert your AR-15 type rifle to shoot the same 5.7x28 ammo as the legendary FN P-90 PDW! This AR57 Upper is constructed with a steel barrel, muzzle brake, bolt carrier group, buffer, …

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 …

Factory New - comes with a 16" lightweight barrel with M-LOK rails. This AR57 AR57 Upper Receiver Assembly converts any AR-15 lower to a rifle capable of shooting 5.7x28 …

This AR57 Upper Receiver Assembly converts any AR-15 lower to a rifle capable of shooting 5.7x28 ammunition. The unique upper design loads from the top and ejects downward through …

The AR57 Upper Receiver Assembly converts an AR-15 to shoot 5.7x28 FN ammunition. The unique upper design loads on top and accepts FN PS90 magazine (not included) and ejects …