First Impressions of CMMG MkGs Resolute Upper Receiver Group
The CMMG MkGs Resolute Upper Receiver Group in .40 S&W offers a unique take on the AR platform, blending the familiar ergonomics with the hard-hitting performance of a pistol caliber. The CMMG name carries weight, known for its innovative approach to firearms, and the Resolute line promises quality and reliability. This upper receiver group immediately piqued my interest as I wanted to explore the potential of a .40 S&W carbine for home defense and recreational shooting.
I’ve been a firearms enthusiast and gear specialist for over a decade, always searching for the next evolution in tactical and sporting arms. My current focus is optimizing a versatile AR-platform, and I wanted to explore alternatives to the ubiquitous 5.56 NATO round. I was particularly interested in the .40 S&W’s potential for delivering significant energy in a compact AR pistol or carbine configuration.
The CMMG MkGs Resolute Upper Receiver Group arrived securely packaged. My initial impression was very positive, due to the build quality of the components and the sleek Armor Black finish. The weight felt balanced, suggesting a well-engineered system ready to mate with a compatible lower receiver.
I considered a similar upper receiver group from another well-known manufacturer, as well as building a custom .40 S&W AR from scratch. However, the CMMG‘s reputation for reliability and the promise of seamless integration with existing AR-15 lowers swayed my decision. The assurance of a complete, factory-built upper receiver group was appealing.
My first impression was one of cautious optimism. I was excited to explore the capabilities of a .40 S&W AR, but wanted to see how it would perform at the range. The overall fit and finish suggested a quality product, but the proof would be in the shooting.
Real-World Testing: Putting CMMG MkGs Resolute Upper Receiver Group to the Test
First Use Experience
I tested the CMMG MkGs Resolute Upper Receiver Group at my local outdoor shooting range. It was a relatively mild day, around 65 degrees Fahrenheit, with a slight breeze, making for comfortable shooting conditions. The range offered distances up to 100 yards.
The CMMG upper performed exceptionally well right out of the box. I experienced no failures to feed or eject in the first 100 rounds. The recoil, while more noticeable than a 5.56, was manageable and pleasant.
I was surprised by the accuracy of the CMMG MkGs Resolute Upper Receiver Group. It delivered tight groupings at 50 yards with ease. I did notice a slight tendency for the muzzle to climb during rapid fire, but that was easily controlled with proper grip and stance.
Extended Use & Reliability
After several months and over 500 rounds, the CMMG MkGs Resolute Upper Receiver Group continues to impress. It has proven to be exceptionally reliable with various brands of .40 S&W ammunition. The upper receiver group maintains its accuracy and consistent performance.
There are no significant signs of wear and tear. The Armor Black finish is holding up well, with only minor scuffs in high-contact areas. Cleaning the CMMG MkGs Resolute Upper Receiver Group is straightforward, thanks to the AR-15 platform’s familiar disassembly process.
This CMMG upper receiver group far outperforms my expectations for a pistol-caliber AR. The accuracy and reliability surpass other pistol-caliber conversions I’ve used. It has become one of my favorite range toys and a strong contender for a home defense setup.
Breaking Down the Features of CMMG MkGs Resolute Upper Receiver Group
Specifications
The CMMG MkGs Resolute Upper Receiver Group features a 16.1-inch medium taper barrel chambered in .40 S&W. The barrel has a 1-16 twist rate. It also has .578×28 threads per inch.
The upper receiver is constructed from billet 6061 T6 aluminum with an Armor Black finish. It weighs 3.9 lbs and has an overall length of 25.3 inches. The M-LOK handguard provides ample space for accessories.
These specifications are critical to the performance of this upper receiver group. The .40 S&W caliber provides significant stopping power. The 16.1-inch barrel maximizes the .40 S&W’s velocity and accuracy potential in a carbine platform.
Performance & Functionality
The CMMG MkGs Resolute Upper Receiver Group delivers excellent performance and functionality. The blowback operating system is simple and reliable. It cycles smoothly with a variety of .40 S&W ammunition.
The accuracy is outstanding, especially at distances of 50-75 yards. The recoil is manageable, making it comfortable to shoot for extended periods. One minor weakness is the potential for muzzle climb during rapid fire.
The CMMG MkGs Resolute Upper Receiver Group exceeds my expectations in terms of accuracy, reliability, and overall user experience. It is a well-engineered product that delivers on its promise.
Design & Ergonomics
The CMMG MkGs Resolute Upper Receiver Group is well-designed and ergonomic. The billet 6061 T6 aluminum construction provides a sturdy and lightweight platform. The Armor Black finish is durable and aesthetically pleasing.
The M-LOK handguard offers ample space for attaching accessories such as lights, lasers, and foregrips. The AR-15 platform’s familiar ergonomics make it easy to adapt to. The only learning curve is understanding the different recoil characteristics of the .40 S&W cartridge compared to a standard 5.56.
Durability & Maintenance
The CMMG MkGs Resolute Upper Receiver Group is built to last. The high-quality materials and construction ensure long-term durability. Regular cleaning and lubrication are essential for maintaining optimal performance.
Disassembly and cleaning are straightforward. The AR-15 platform is known for its ease of maintenance and repair. With proper care, this upper receiver group should provide years of reliable service.
Accessories and Customization Options
The CMMG MkGs Resolute Upper Receiver Group does not come with any accessories. The M-LOK handguard allows for easy attachment of aftermarket accessories like vertical grips, lights, and lasers. It’s compatible with most AR-15 lowers designed to accept Glock magazines, as well as .40 S&W magazines.
The upper receiver is compatible with a wide range of AR-15 optics, including red dot sights, holographic sights, and scopes. The .578×28 threaded barrel allows for the attachment of various muzzle devices, such as suppressors and compensators. The options for customization are limitless, allowing users to tailor the rifle to their specific needs and preferences.
Pros and Cons of CMMG MkGs Resolute Upper Receiver Group
Pros
- Excellent Accuracy: Delivers tight groupings at 50-75 yards.
- Reliable Performance: Cycles smoothly with various .40 S&W ammunition.
- Durable Construction: Billet 6061 T6 aluminum with a robust Armor Black finish.
- M-LOK Handguard: Provides ample space for attaching accessories.
- Unique Caliber: The .40 S&W offers a unique and potent option for an AR platform.
Cons
- Muzzle Climb: Can exhibit some muzzle climb during rapid fire.
- Price: The initial investment is relatively high compared to building a standard AR-15 upper.
Who Should Buy CMMG MkGs Resolute Upper Receiver Group?
The CMMG MkGs Resolute Upper Receiver Group is perfect for:
- Home defense enthusiasts seeking a potent and maneuverable platform.
- Hobbyist shooters looking for a unique and exciting addition to their collection.
- Competitive shooters who want to explore the .40 S&W caliber in PCC (Pistol Caliber Carbine) competitions.
This product might not be ideal for:
- Budget-conscious buyers looking for the most affordable AR-15 option.
- Those unfamiliar with the AR-15 platform, as some assembly and maintenance knowledge is required.
Must-have accessories or modifications:
- A quality red dot sight for fast target acquisition.
- A comfortable and ergonomic pistol grip.
- A muzzle brake or compensator to mitigate muzzle climb.
Conclusion on CMMG MkGs Resolute Upper Receiver Group
The CMMG MkGs Resolute Upper Receiver Group in .40 S&W offers a unique and compelling package for those seeking a potent and reliable AR-platform. It provides excellent accuracy, reliable performance, and a durable construction. The .40 S&W caliber offers a distinct advantage in terms of stopping power compared to other pistol calibers.
The price is certainly an investment, but the quality and performance justify the cost. I would highly recommend the CMMG MkGs Resolute Upper Receiver Group to anyone looking to explore the .40 S&W caliber in an AR platform.
If you’re looking for a well-built, reliable, and accurate pistol caliber carbine upper, the CMMG MkGs Resolute Upper Receiver Group is definitely worth considering. Upgrade your AR today and experience the power of the .40 S&W!