The CMMG Resolute MK57 is a semi-automatic rifle chambered in 5.7x28mm. The cartridge's low recoil and flat trajectory make it a practical choice for sport shooting and home defense. 
 

Key Specifications 

• Model: Resolute MK57 
• Caliber: 5.7 x 28mm 
• Action: Semi-Automatic 
• Barrel Length: 16.1 inches 
• Capacity: 20 rounds (1 magazine included) 
• Finish: Black Cerakote 
• Manufacturer: CMMG 
• Condition: New in Box 
   

Features 

The ZEROED pistol grip is shaped for a consistent hold and comfortable handling. The ambidextrous safety operates at 60 or 90 degrees, which works for both left- and right-handed shooters without modification. An ambidextrous AR15 charging handle makes cycling the action straightforward. The AR15 bolt catch and polymer dust cover are standard inclusions, and the muzzle brake cuts felt recoil noticeably for faster follow-up shots. 
 
The 5.7x28mm caliber keeps the rifle light and controllable. Target shooters appreciate the low recoil during practice sessions, and the 20-round capacity gives enough rounds for most defensive or competition use without the added bulk of a larger-format rifle.

Users discussing the CMMG Resolute MK57 generally land in two camps: those who like the 5.7x28mm platform and those who question its cost relative to more common calibers.

On the positive side, the rifle's versatility gets consistent mention. Owners appreciate that it works for target shooting, home defense, and varmint hunting. The 5.7x28mm round's low recoil and high velocity are frequently cited. It's easy to shoot quickly and accurately, and muzzle rise is minimal even during rapid fire. The lightweight build and modular features earn praise as well, particularly from shooters who want a compact rifle without giving up magazine capacity.

Ergonomics come up often. The adjustable stock and overall handling characteristics sit well with a range of body types and experience levels, making it accessible to newer shooters.

On the critical side, reliability with certain ammunition types and magazine compatibility draw some complaints. Some users report that the rifle is more sensitive to ammo selection than comparable AR-pattern rifles. Pricing is another recurring topic. Opinions split between those who find the cost reasonable for the platform and those who feel they could get more firepower in a more common caliber for less money.

Aftmarket support is generally seen as a plus. Parts and accessories are available, and owners share modification tips in the 5.7 community. Overall sentiment leans positive among shooters specifically interested in the 5.7x28mm format, with the main reservations tied to price and ammo pickiness.