First Impressions of CMMG DISSENT Mk4, 300BLK, 10.5in Upper Receiver
The CMMG DISSENT Mk4, 300BLK, 10.5in Upper Receiver promises a compact and versatile solution for building a 300 Blackout AR pistol. Manufactured by CMMG, this upper receiver stands out due to its bufferless design and forward non-reciprocating side charger. The integrated action and recoil assembly within the upper receiver itself eliminate the need for a traditional buffer tube, opening a new realm of possibilities for compact builds.
I was looking for a high-quality upper receiver that could form the core of my new, extremely compact 300 Blackout AR pistol build, something easily stowed in a backpack. The CMMG DISSENT Mk4 immediately caught my eye because of its innovative bufferless design, and the promise of improved ballistics with the 10.5-inch barrel. The absence of a buffer tube was a huge factor, as it opened the door to significantly reduce the overall length of my build.
Unboxing the CMMG DISSENT, I was immediately impressed with the fit and finish. The anodized aluminum felt robust and the side charging handle moved with a satisfying smoothness. The weight felt balanced, giving the impression of a solid, well-engineered piece of kit.
I considered the BRN-180SH upper receiver and the Maxim Defense MD-15 upper, but the CMMG DISSENT’s inclusion of a 1913 Picatinny rail end plate for brace/stock attachment directly sealed the deal, and the CMMG reputation for quality gave me peace of mind.
My initial reaction was pure excitement, mixed with a healthy dose of anticipation. I was eager to see how this innovative upper receiver would perform on the range and whether it could live up to its promise of a compact and reliable 300 Blackout platform.
Real-World Testing: Putting CMMG DISSENT Mk4, 300BLK, 10.5in Upper Receiver to the Test
First Use Experience
My first outing with the CMMG DISSENT Mk4 was at my local outdoor shooting range. I was particularly interested in testing its reliability with both supersonic and subsonic ammunition, and seeing how the recoil impulse differed from traditional AR platforms. The weather was clear and sunny, providing ideal conditions for zeroing the optic and getting a feel for the rifle.
The CMMG DISSENT ran flawlessly straight out of the box. I experienced no malfunctions with either supersonic or subsonic ammunition, even with various grain weights. The side charging handle proved intuitive and easy to manipulate, allowing for quick reloads and malfunction clearing without breaking my sight picture.
The only initial surprise was the slightly different recoil impulse compared to a standard AR-15 with a buffer tube. It felt more direct and perhaps a tad sharper, but manageable and predictable.
Extended Use & Reliability
After several months of regular use, the CMMG DISSENT Mk4 has proven to be exceptionally reliable. It has endured multiple range trips and a few backcountry hikes in varying weather conditions, including light rain and dusty environments. The upper receiver continues to function flawlessly, with no signs of degradation in performance.
The finish shows some minor wear marks on the ejection port and around the charging handle, but this is expected with regular use. Cleaning and maintenance are straightforward; the action disassembles easily and all components are readily accessible. Compared to my experiences with other AR-15 uppers, the CMMG DISSENT is relatively easy to clean due to its simpler internal design.
It has exceeded my expectations for reliability and compactness. This has become my go-to choice for situations where portability and discretion are paramount.
Breaking Down the Features of CMMG DISSENT Mk4, 300BLK, 10.5in Upper Receiver
Specifications
The CMMG DISSENT Mk4, 300BLK, 10.5in Upper Receiver boasts several key specifications that contribute to its performance. It is chambered in .300 AAC Blackout, a versatile cartridge suitable for both supersonic and subsonic applications. The 10.5-inch barrel strikes a good balance between maneuverability and ballistic performance in the 300BLK cartridge.
The barrel features a 1-7 twist rate, which effectively stabilizes a wide range of bullet weights commonly used in 300BLK. The 5/8×24 threads per inch at the muzzle allow for easy attachment of suppressors and other muzzle devices. It is constructed primarily from aluminum, keeping the weight down while maintaining structural integrity.
The handguard features M-LOK slots for easy attachment of accessories. This upper receiver is designed for the CMMG Mk4 platform and is a testament to CMMG’s engineering prowess. The absence of an included magazine should be noted for budgeting purposes.
Performance & Functionality
The CMMG DISSENT Mk4 performs exceptionally well as a complete upper receiver. Its accuracy is more than adequate for its intended purpose, allowing for tight groupings at typical pistol ranges. The reliability is outstanding, with consistent cycling and minimal malfunctions even with a variety of ammunition types.
One notable strength is the non-reciprocating side charging handle, which allows the user to maintain a consistent cheek weld while manipulating the bolt. The direct impingement Compact Action system ensures smooth and reliable operation. A minor weakness could be the slightly sharper recoil impulse compared to a traditional AR-15 with a buffer system, but this is a trade-off for the increased compactness.
It has exceeded my expectations in terms of both performance and innovative design.
Design & Ergonomics
The CMMG DISSENT’s design is centered around compactness and functionality. The bufferless design drastically reduces the overall length of the firearm, making it ideal for use in confined spaces or for discreet carry. The side charging handle is ergonomically placed and easy to reach, even with gloves.
The build quality is excellent, with tight tolerances and a durable finish. While it might require a bit of familiarization for users accustomed to traditional AR-15 platforms, the learning curve is relatively short. The intuitive controls and well-thought-out layout make it easy to operate.
Durability & Maintenance
With proper care, the CMMG DISSENT Mk4 should provide years of reliable service. The aluminum construction is resistant to corrosion and wear. Regular cleaning and lubrication are essential for maintaining optimal performance.
Disassembly is straightforward, allowing for easy access to critical components. Replacement parts are readily available from CMMG and other aftermarket suppliers.
Accessories and Customization Options
The CMMG DISSENT Mk4 comes with a 1913 Picatinny rail end plate, allowing for easy attachment of various braces or stocks. The M-LOK handguard provides ample space for mounting accessories such as lights, lasers, and foregrips. The 5/8×24 threaded muzzle allows for the use of suppressors, muzzle brakes, and flash hiders.
It is compatible with a wide range of AR-15 accessories, including optics, triggers, and magazines. Many users choose to upgrade the trigger for improved feel and performance.
Pros and Cons of CMMG DISSENT Mk4, 300BLK, 10.5in Upper Receiver
Pros
- Incredibly compact design due to the bufferless system.
- Reliable operation with both supersonic and subsonic ammunition.
- Non-reciprocating side charging handle for improved ergonomics.
- High-quality construction and durable finish.
- Easy to customize with readily available AR-15 accessories.
Cons
- Slightly sharper recoil impulse compared to traditional AR-15 platforms.
- Relatively high price point.
Who Should Buy CMMG DISSENT Mk4, 300BLK, 10.5in Upper Receiver?
The CMMG DISSENT Mk4 is perfect for individuals seeking an extremely compact and reliable 300 Blackout platform. It is well-suited for those who prioritize portability and discretion, such as backcountry adventurers or those who need a easily-stowed defensive firearm. It also appeals to those building AR pistols and wanting to circumvent the buffer tube design.
This product might not be ideal for budget-conscious buyers or those who prefer the familiar recoil characteristics of a traditional AR-15.
A must-have accessory is a high-quality brace or stock (depending on local regulations). A reliable optic (red dot or LPVO) is also highly recommended for maximizing accuracy.
Conclusion on CMMG DISSENT Mk4, 300BLK, 10.5in Upper Receiver
The CMMG DISSENT Mk4, 300BLK, 10.5in Upper Receiver is an innovative and well-engineered product that delivers on its promise of compactness and reliability. While the price is a bit steep, the quality, performance, and unique features justify the investment for those who prioritize these attributes. The value proposition is strong, especially for users who need a compact and dependable 300 Blackout firearm.
I would highly recommend the CMMG DISSENT Mk4 to anyone looking for a top-tier bufferless upper receiver. It’s a game-changer in the world of AR pistols. If you value innovation, quality, and compactness, the CMMG DISSENT is worth every penny. Invest in the CMMG DISSENT Mk4 and experience the future of compact AR platforms!