The CMMG Resolute MK4 is a direct impingement rifle chambered in .300 AAC Blackout with a 16.1-inch barrel. At 6.2 lbs and 32.5 inches overall, it's a manageable package for either range use or home defense. The 30-round Magpul PMAG is included. 
 

Key Specifications 

• Caliber: .300 AAC Blackout 
• Barrel Length: 16.1 inches 
• Capacity: 30 rounds (Magpul PMAG) 
• Weight: 6.2 lbs 
• Overall Length: 32.5 inches 
• Operating System: Direct Impingement 
• Finish Color: Cerakote Black 
• Manufacturer: CMMG 
• Model Number: Resolute MK4 
   

Detailed Features 

The upper receiver is billet 6061 T6 aluminum; the lower is forged 7075 T6 aluminum, a combination that keeps weight down without sacrificing durability. The CMMG EML15 M-LOK handguard has plenty of real estate for lights, lasers, or a foregrip. Stock is the CMMG RipStock with adjustable length-of-pull. The ZEROED drop-in trigger has a smooth pull and a clean break, which helps with accuracy at distance. 
 
The .300 AAC Blackout works with both subsonic and supersonic loads, which makes the MK4 a natural fit for suppressor use if that's on the table. With supersonic ammo it performs similarly to other mid-range sporting rifles; with subsonics it gets noticeably quieter with a can attached.

The CMMG Resolute MK4 in .300 Blackout gets generally favorable reviews, with build quality cited most often. CMMG's reputation for fit, finish, and durability holds up here. The attention to tolerances is something owners notice and mention. The .300 Blackout caliber is consistently praised for its flexibility with subsonic ammo, making it a popular choice for target shooting and hunting.

Accuracy and handling get positive marks across different conditions. The adjustable gas system is a feature owners actually use. It lets them tune the rifle's performance to different ammo loads or suppressor configurations, and that's the kind of thing that matters when you're switching between supersonic and subsonic rounds regularly.

The main criticisms are price and weight. The MK4 costs more than several competitors in the .300 Blackout segment, and some shooters feel the weight could be trimmed for better handling on longer outings. Neither complaint is a dealbreaker for most owners, but both come up in comparisons.

Magazine compatibility is generally fine with standard .300 Blackout magazines, though ammo availability and pricing in some regions draws occasional frustration. That's more a caliber issue than a rifle issue.