MPN: 99B518D-AB


  • Radial Delayed Blowback System - softer recoil impulse and reduced bolt weight
  • Caliber: 9mm
  • Finish: Armor Black Cerakote, Sniper Grey, or Coyote Tan
  • Upper Receiver: CMMG Mk4 Upper Receiver - 6061-T6 Aluminum
  • Handguard: 7-Inch CMMG EML7 Handguard
  • Muzzle Device: CMMG 9mm ZEROED Linear Compensator
  • Barrel: 8" 1:10 Salt Bath Nitrided 4140 Chrome Moly Steel
  • Muzzle Thread Pattern: 1/2"-28
  • Bolt Carrier Group: CMMG 9mm MkGs 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: ~2.9 lbs.
  • Length: ~16.19"


  • AR-15 lower receiver with AR9 conversion magazine
  • CMMG Mk9 lower receiver with Colt-pattern magazine
  • CMMG MkGs lower receiver with Glock-pattern magazine
  • CMMG Mk17 lower receiver with Sig P320 magazine


  • 1x CMMG Banshee 9mm 8" MK4 Complete Upper
  • 1x CMMG 9mm MkGs Bolt Carrier Group
  • 1x CMMG ZEROED AR15 Ambi Charging Handle


Pistol Caliber Carbines make for excellent home defense weapons and PDWs. They are easy to control, maneuverable, and have a lot more firepower than a handgun. Moreover, they can be more fun to shoot at the range and much more affordable than rifles.

If you want to build a 9mm AR pattern PCC, there are a few options as good as the CMMG Banshee 9mm MK4 upper. This upper assembly comes with an 8-inch Salt Bath Nitrided 4140 Chrome Moly Steel barrel. CMV steel barrels are more durable and better at heat dissipation than normal steel barrels. The CMMG Banshee Mk4 Upper barrel comes with a 1:10 twist rifling profile, which allows for excellent performance with a wide range of 9mm bullet weights and profiles. Moreover, this barrel is equipped with a CMMG 9mm ZEROED Linear Compensator, significantly decreasing perceived recoil and muzzle flip.

This upper assembly features a 7-Inch CMMG EML7 Handguard. This slim profile handguard is made from 6061-T6 Aluminum and has M-LOK slots on the sides and the bottom, with a full-length Picatinny rail on top.

Unlike most 9mm PCCs, which have a simple straight blowback operating system, the CMMG Banshee Mk4 upper uses a Radial Delayed Blowback system, which results in a softer recoil impulse, and allows the bolt to be lighter as well. The Mk4 receiver comes with a CMMG 9mm MkGs Bolt Carrier Group, which is compatible with all 9mm AR lowers, whether they use Colt-style or Glock-style magazines. Lastly, this upper assembly gets a CMMG ZEROED AR15 Ambi Charging Handle. 

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  • This Item: CMMG Banshee 9mm 8" MK4 Complete Upper
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