The CMMG Banshee in 5.7x28mm with a 5-inch barrel is the shorter-barreled configuration of the platform, weighing 4.8 lbs and holding 40+1 rounds. The ambidextrous safety lever works for both left- and right-handed shooters, and there are no factory sights so you start with a clean optics rail. 
 

Key Specifications 

• SKU: 2024036498 
• UPC: 810148624194 
• Condition: New in Box 
• Safety: Ambidextrous Safety Lever 
• Trigger: Standard 
• Grip: CMMG Zeroed 
• Weight: 4.8 lbs 
• Sights: None (optics-ready) 
• Barrel Length: 5" 
• Capacity: 40+1 RD 
• Action: Semi-Auto 
• Caliber: 5.7x28mm 
• MPN: 54A3B0FMB 
• Model Name: Banshee 
• Brand: CMMG 
   
  The 5-inch barrel gives up some velocity compared to the 8-inch version but keeps the overall package more maneuverable. Forty rounds in the magazine is a significant capacity advantage in a pistol-format carbine. The 5.7x28mm cartridge produces low felt recoil at 4.8 lbs overall, which makes fast follow-up shots manageable. Standard trigger and CMMG Zeroed grip ship as-is, no break-in modifications needed.

Owners of the CMMG Banshee in 5.7x28mm generally respond positively, with a few consistent areas of debate.

The compact size and light weight get the most frequent praise. The 5.7x28mm chambering is seen as a differentiator, and users appreciate the low recoil for a caliber with that kind of velocity. The 40+1 capacity is a genuine draw for range use and for anyone building a defensive carbine.

Ammunition cost and availability are the main complaints. 5.7x28mm runs more expensive than common pistol calibers and is not always easy to source locally, which affects how often some owners can shoot it. Price of the gun itself draws mixed reactions; some consider it fair for the platform's features, others feel it is high relative to 9mm-chambered competitors. A handful of users have reported reliability issues, though these appear to be unit-specific rather than a pattern across the model. Aftermarket support is seen as a plus for those who want to customize.