First Impressions of CMMG DISSENT Mk4, 300BLK, 6.5in Upper Receiver
The CMMG DISSENT Mk4, 300BLK, 6.5in Upper Receiver promised to be a game-changer in the world of compact personal defense weapons, and I was eager to see if it lived up to the hype. As someone with over a decade in the tactical gear world, I’ve seen my fair share of innovations, and the DISSENT’s bufferless design immediately caught my attention. This upper receiver aims to deliver .300 Blackout power in an incredibly small package, all while maintaining AR-15 compatibility.
Years of lugging around rifles and SBRs made me yearn for a more compact option without sacrificing ballistic performance. I was looking for a solution for home defense and vehicle carry, something easily stowed but ready for immediate action. The promise of a 6.5-inch .300 Blackout build that still utilizes a standard AR-15 lower seemed like the perfect answer.
The unboxing experience was straightforward; the upper receiver arrived well-packaged. My initial impression was dominated by the DISSENT’s compact size and solid feel. The Cerakote finish was flawless, and the M-LOK handguard felt robust.
Compared to something like a SIG Rattler upper, the CMMG DISSENT stands out due to its compatibility with standard AR-15 lowers and a more affordable price point. While the Rattler is undeniably a premium option, the DISSENT offers a compelling balance of features and value. Another option, the Maxim Defense MDX, also boasts compactness, but again, the DISSENT’s AR lower compatibility and price swayed me. I wanted to maintain parts commonality and save some cash.
My first impression was overwhelmingly positive, a mixture of excitement and cautious optimism. The CMMG DISSENT Mk4, 300BLK, 6.5in Upper Receiver had the potential to be a game-changer, but the real test would be its performance in the field.
Real-World Testing: Putting CMMG DISSENT Mk4, 300BLK, 6.5in Upper Receiver to the Test
First Use Experience
My first range trip with the CMMG DISSENT Mk4, 300BLK, 6.5in Upper Receiver was conducted at an outdoor range under relatively mild conditions. I primarily focused on accuracy at 25 and 50 yards, as well as reliability with various .300 Blackout loads, both supersonic and subsonic. The humidity was moderate, but there was little to no wind.
The DISSENT ran surprisingly well straight out of the box. It cycled both supersonic and subsonic ammunition without any issues after the initial break-in period. Accuracy was acceptable for a short-barreled .300 Blackout, achieving roughly 2-3 MOA with my preferred supersonic load.
The side charging handle took a bit of getting used to, but it proved to be incredibly efficient once I adjusted my technique. There were no initial issues, although the linear compensator directed a significant amount of blast back toward the shooter, something to be mindful of when shooting indoors or in confined spaces.
Extended Use & Reliability
After several months of use, the CMMG DISSENT Mk4, 300BLK, 6.5in Upper Receiver has proven to be a reliable platform. I’ve used it in several training courses, as well as during a few hunting trips in moderately adverse conditions (light rain and dusty environments). The finish has held up remarkably well, with only minor wear marks appearing on high-friction areas.
The DISSENT requires slightly more frequent cleaning than a standard AR-15 due to the direct impingement Compact Action being contained within the upper receiver. However, cleaning is still relatively straightforward. I’ve found that a good quality CLP and a thorough brushing are sufficient for maintaining its reliability.
Compared to my previous experiences with other short-barreled AR platforms, the CMMG DISSENT offers a significantly more compact package without a noticeable reduction in ballistic performance at close ranges. It has exceeded my expectations for reliability and ease of use.
Breaking Down the Features of CMMG DISSENT Mk4, 300BLK, 6.5in Upper Receiver
Specifications
The CMMG DISSENT Mk4, 300BLK, 6.5in Upper Receiver is chambered in .300 AAC Blackout. This caliber offers excellent performance in short-barreled platforms, providing significant stopping power at close to medium ranges.
It features a 6.5-inch barrel. This short barrel length contributes to the overall compactness of the platform, making it ideal for use as a PDW.
The barrel has a 1-7 twist rate, optimized for stabilizing a wide range of .300 Blackout bullet weights, including both supersonic and subsonic loads.
The muzzle is threaded 5/8×24, allowing for the attachment of various muzzle devices, including suppressors.
It includes a Zeroed Linear Compensator. This device redirects the muzzle blast forward, reducing perceived recoil and muzzle rise, especially helpful with a short barrel.
The upper receiver is constructed from aluminum, providing a lightweight and durable platform.
The handguard features M-LOK slots, allowing for the attachment of various accessories, such as lights, lasers, and grips.
It is designed for use with a CMMG Mk4 lower or standard AR-15 lower receiver. This compatibility makes it a versatile option for existing AR-15 owners.
The DISSENT operates with a patent-pending direct impingement Compact Action. This system eliminates the need for a buffer tube, significantly reducing the overall length of the firearm.
The end plate features a 1913 Picatinny rail for mounting stocks or braces.
Performance & Functionality
The CMMG DISSENT Mk4, 300BLK, 6.5in Upper Receiver performs admirably in its intended role as a compact personal defense weapon. Its accuracy is more than sufficient for close-quarters engagements. The reliability of the action, even with a variety of .300 Blackout loads, inspires confidence.
Its primary strength lies in its compactness and AR-15 lower compatibility, while the muzzle blast from the linear compensator could be improved with a different muzzle device option. It meets expectations as a compact, reliable .300 Blackout upper receiver.
Design & Ergonomics
The build quality of the CMMG DISSENT is excellent. The aluminum upper receiver feels solid and well-made. The weight is well-balanced, making it comfortable to handle.
The side-charging handle is intuitive and easy to use once accustomed to its location and action. There is a slight learning curve compared to a traditional AR-15 charging handle.
Durability & Maintenance
With proper care, the CMMG DISSENT Mk4, 300BLK, 6.5in Upper Receiver should last for many years. The aluminum construction and Cerakote finish provide excellent resistance to corrosion and wear.
The DISSENT is relatively easy to maintain. Regular cleaning and lubrication are essential to ensure reliable operation.
Accessories and Customization Options
The CMMG DISSENT Mk4, 300BLK, 6.5in Upper Receiver does not come with many included accessories beyond the linear compensator and Picatinny rail end plate. However, it is highly customizable.
The M-LOK handguard allows for the attachment of various accessories. The 5/8×24 muzzle threads make it compatible with a wide range of muzzle devices and suppressors. It is compatible with any standard AR-15 lower receiver.
Pros and Cons of CMMG DISSENT Mk4, 300BLK, 6.5in Upper Receiver
Pros
- Extremely compact size ideal for vehicle carry and home defense.
- Reliable operation with both supersonic and subsonic .300 Blackout ammunition.
- AR-15 lower compatibility for versatility and cost savings.
- Durable construction with aluminum receiver and Cerakote finish.
- Side-charging handle offers enhanced ergonomics.
Cons
- Significant muzzle blast from the linear compensator.
- Slightly more complex cleaning than a standard AR-15.
Who Should Buy CMMG DISSENT Mk4, 300BLK, 6.5in Upper Receiver?
The CMMG DISSENT Mk4, 300BLK, 6.5in Upper Receiver is perfect for individuals seeking a compact and reliable personal defense weapon. It’s ideal for home defense, vehicle carry, and anyone needing a highly concealable, yet powerful, platform. This is also great for firearm enthusiasts who want to experiment with different AR-15 configurations.
Those prioritizing maximum long-range accuracy or requiring a platform that can handle extreme environmental conditions might want to consider other options. Shooters sensitive to muzzle blast may want to invest in a different muzzle device.
A brace or stock, optic, weapon light, and sling are must-have accessories for the CMMG DISSENT.
Conclusion on CMMG DISSENT Mk4, 300BLK, 6.5in Upper Receiver
The CMMG DISSENT Mk4, 300BLK, 6.5in Upper Receiver delivers on its promise of compact .300 Blackout performance. Its innovative bufferless design and AR-15 lower compatibility make it a compelling option for those seeking a highly concealable and reliable personal defense weapon.
While the price is not inexpensive, the value proposition is strong given the innovative design and performance. I would personally recommend it to anyone looking for a compact .300 Blackout platform without the hassle of proprietary lowers or buffer systems.
If you’re in the market for a cutting-edge PDW upper receiver, the CMMG DISSENT Mk4, 300BLK, 6.5in Upper Receiver is definitely worth considering. Upgrade your AR-15 lower today and experience the future of compact firepower!