Radian Weapons 18" 6mm ARC Complete Upper Receiver FDE

Radian machines complete uppers to the same standard as their rifles, and this one brings 6mm ARC to your AR-15 lower in one bolt on package. The 18 inch barrel gives the cartridge enough velocity to do what 6mm ARC was designed for: supersonic precision well past 1,000 yards from a gas gun, with roughly half the recoil of the big short magnums that used to own that distance.

The FDE finish covers the upper and handguard as a matched set, and the machining tolerances Radian built its reputation on show up in how the parts fit. Drop it on any mil spec AR-15 lower, feed it from 6mm ARC magazines, and you have a legitimate long range gas gun without building from a parts list.