MPN: 30B81F4-AB


  • Caliber: .300 Blackout
  • Finish: Armor Black Cerakote
  • Upper Receiver: CMMG Mk4 Upper Receiver - 6061-T6 Aluminum
  • Handguard: 7-Inch CMMG EML7 Handguard
  • M4 Feed Ramps: Yes
  • Muzzle Device: CMMG .308 ZEROED Linear Compensator
  • Barrel: 8" 1:7 Salt Bath Nitrided 4140 Chrome Moly Steel
  • Muzzle Thread Pattern: 5/8"-24
  • Gas Block: Aero .750" Low-Profile Gas Block
  • Gas Tube: Pistol-Length Gas Tube
  • Bolt Carrier Group: Mil-Spec M16 Bolt Carrier Group
  • Charging Handle: CMMG ZEROED AR15 Ambi Charging Handle
  • HP and MPI Tested

*This upper receiver assembly has a barrel that is shorter than 16". This upper is only for use on AR pistol lower receivers and NFA registered Short-Barreled Rifle (SBR) lower receivers. All NFA laws apply!


  • Weight: ~3.03 lbs.
  • Length: ~16.19"


  • AR-15 lower receiver


  • 1x CMMG Banshee 300 Blackout 8" MK4 Complete Upper


If you are looking for a powerful and effective short personal defense weapon, the CMMG Banshee MK4 chambered in .300 Blackout is a perfect option.

The CMMG Banshee 300 Blackout MK4 Upper comes in multiple configurations. However, this pistol version comes with a short 8-inch barrel. This works great with the .300 blackout caliber, as it was designed to be fired from a short barrel and can reach its maximum burning potential in a 9-inch barrel.

The barrel on this upper is made from Salt Bath Nitrided 4140 Chrome Moly Steel barrel. It is stronger than standard stainless steel barrels and has better corrosion resistance qualities as well. It has a 5/8"-24 thread pitch and comes with a CMMG .308 ZEROED Linear Compensator. This compensator does a great job of decreasing felt recoil and muzzle rise.

The gas block on this upper has a low profile and features a pistol-length gas tube. It is covered by a 7-inch CMMG EML7 M-LOK Handguard, which has M-LOK slots on both sides and the bottom, along with two small sections of Picatinny rail on the top.

The receiver itself is made from 6061-T6 Aluminum and is chambered in .300 Blackout. It features M4 feed ramps for feeding reliability and uses a Mil-Spec M16 bolt carrier group and the CMMG ZEROED ambidextrous charging handle. The steel of the barrel and BCG are high pressure tested, and magnetic particles inspected to make sure it doesn't have any micro imperfections.

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  • This Item: CMMG Banshee 300 Blackout 8" MK4 Complete Upper
    MSRP: $849.95
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