The CMMG Resolute 100 is a semi-automatic rifle chambered in 5.7x28mm. The caliber is the defining choice here — low recoil, high velocity, and 20 rounds on tap make it genuinely different from a standard .223 carbine. At 8.6 lbs it's on the heavier side for an AR-pattern gun, but the tradeoff is a smooth shooting cycle that stays on target. 
 

Key Specifications 

• Manufacturer: CMMG 
• Model: Resolute 100 
• Type: Modern Sporting Rifle (AR) 
• Caliber: 5.7 x 28mm 
• Barrel Length: 16.1 inches 
• Capacity: 20 rounds 
• Weight: 8.6 lbs. 
• Condition: New in Box 
• Finish Color: Black 
   

Detailed Features 

The polymer stock and grip hold up under hard use and keep handling predictable during rapid fire. Barrel twist is 1:9, which stabilizes the 5.7 round well across practical distances. Semi-auto action allows quick follow-up shots without any manual cycling. 
 
The main real-world consideration with this caliber is ammunition availability — 5.7x28mm is less common on store shelves than .223 or 9mm, and tends to cost more per round. Worth factoring in before committing to the platform.

The CMMG Resolute 100 in 5.7x28mm draws consistent interest from shooters who want something different from the usual AR-15 lineup. The 5.7x28mm cartridge is the main talking point: low recoil, flat trajectory, and high velocity that lets shooters stay on target through quick strings. Accuracy gets positive marks, with tight groupings reported at practical distances.

Ammo availability and cost come up in nearly every discussion. The 5.7 round is harder to find than .223 or .308 and runs more expensive per shot, which matters if you shoot regularly. Some users factor that into whether the platform makes long-term sense for them.

On the customization side, the rifle accepts a range of AR-compatible accessories and the modularity is a draw for people who like to build out their guns. Criticism tends to be component-specific rather than platform-wide — occasional comments about parts that feel like candidates for upgrade out of the box. Overall the reception is positive, with most buyers valuing the innovation of the caliber while going in clear-eyed about the ammo situation.