These upper receiver groups begin with a T-marked government-contract M-4 upper receiver laser engraved with our logo.  Barrel flanges are lapped and "trued" for top-notch accuracy.  Builds feature mid-length Adaptive Defense Armory rifle-length handguards and gas blocks with black nitrided gas tubes.   Uppers are headspace checked and test-fired.  

Options include:

• Bolt: No bolt, Phosphated mil-spec bolt, Nitrided "enhanced" bolt
• Charging Handle: No charging handle, USGI, or Adaptive Defense Co-branded "Rack" charging handle by Battle Arms Development.
• Flash Hider: None, USGI A2, or Adaptive Defense "Rook."