300 BLACKOUT AR-15 Upper Receiver Assemblies featuring Milspec 7075 T6 Aluminum Upper Receivers, 416R Stainless Steel or Melonite / Nitride 4150 CMV Barrels, Low Profile Gas Blocks, M-LOK or Keymod Handguards, Flash hiders, Muzzle Brakes, BCGs, Bolt Carrier Groups - Nitride or Nickel Boron
