First Impressions of CMMG Dissent Mk4 .22 ARC 16.1 Upper Group
The CMMG Dissent Mk4 .22 ARC 16.1 Upper Group immediately intrigued me with its promise of modularity and the unique .22 ARC chambering. CMMG‘s reputation for innovative AR platform designs precedes them, and the Dissent’s compact action piqued my interest. The idea of a complete upper receiver group that could transform any mil-spec AR-15 lower into a .22 ARC carbine, without the need for a buffer tube, was incredibly appealing.
I was seeking a lightweight, low-recoil, and accurate platform for training and small game hunting. I already owned several AR-15s in 5.56 NATO, but I wanted something different, something tailored for longer-range .22 shooting than a traditional .22 LR AR conversion could offer. The CMMG Dissent Mk4 .22 ARC 16.1 Upper Group appeared to bridge the gap, offering AR ergonomics with rimfire ballistics optimized for a rifle platform.
Upon unboxing, the first thing I noticed was the solid feel and clean lines. The aluminum receiver felt substantial, and the M-LOK handguard provided ample space for accessories. The forward side-charging handle was smooth and intuitive. Compared to a standard AR upper, the Dissent felt noticeably shorter and more compact. This was immediately preferable to other .22 AR conversion kits, which often feel like afterthoughts rather than integrated designs. Compared to building a dedicated .22 AR from scratch, this was more affordable and offered the flexibility of caliber conversion with a simple upper swap. My initial impression was excitement – this appeared to be a well-engineered and purpose-built upper receiver group.
Real-World Testing: Putting CMMG Dissent Mk4 .22 ARC 16.1 Upper Group to the Test
First Use Experience
My initial testing took place at an outdoor shooting range on a sunny afternoon. The CMMG Dissent Mk4 .22 ARC 16.1 Upper Group was mounted on a mil-spec AR-15 lower receiver I already owned. Right away, the reduced recoil and muzzle rise were noticeable compared to my 5.56 NATO AR. The .22 ARC round, while still a rimfire, offers more punch than a .22 LR. I found the side-charging handle particularly convenient, allowing me to maintain my cheek weld and sight picture while cycling the action.
The first few magazines ran flawlessly. However, after about 100 rounds, I experienced a few failures to extract, which seemed to be ammunition-related. Switching to a different brand of .22 ARC ammunition resolved the issue. It’s important to note that rimfire ammunition can be finicky. Overall, the first experience was positive, with the CMMG Dissent Mk4 .22 ARC 16.1 Upper Group demonstrating good accuracy and ease of use.
Extended Use & Reliability
After several months of use, the CMMG Dissent Mk4 .22 ARC 16.1 Upper Group has proven to be a reliable and enjoyable platform. I’ve put several hundred rounds through it at this point. The upper has held up well to regular use. I’ve seen no significant wear and tear on the receiver or barrel. Maintenance is straightforward. The bolt is easily accessible for cleaning, and the direct impingement system is simple to maintain.
Compared to my experiences with .22 LR AR conversion kits, the Dissent is a significant upgrade. The .22 ARC cartridge delivers flatter trajectories and better accuracy at longer ranges. It has exceeded my expectations for a rimfire AR platform. It has solidified itself as an excellent training tool and a fun plinker.
Breaking Down the Features of CMMG Dissent Mk4 .22 ARC 16.1 Upper Group
Specifications
- Caliber: .22 ARC (Advanced Rifle Cartridge). This caliber offers improved ballistics over .22 LR, making it suitable for longer-range shooting.
- Overall Length: 25.5 inches. The compact design makes it easy to maneuver in tight spaces.
- Barrel Length: 16.1 inches. This barrel length provides a good balance of accuracy and maneuverability.
- Barrel Twist Rate: 1-7. The fast twist rate is optimized for stabilizing the .22 ARC projectile.
- Threads per Inch: 1/2×28. This is a standard thread pitch for .22 caliber firearms, allowing for easy attachment of muzzle devices.
- Muzzle Device: CMMG Zeroed Muzzle Brake. This muzzle brake helps to reduce recoil and muzzle rise.
- Fabric/Material: Aluminum. The aluminum construction keeps the weight down while providing excellent durability.
- Gas Block Journal Size-Diameter: .750 in. This is a standard size, providing compatibility with aftermarket gas blocks if desired.
- Gun Rail: M-LOK. The M-LOK rail provides ample space for attaching accessories.
- Weight: 5.05 lb. The lightweight design makes it easy to carry for extended periods.
- Barrel Material: 4140 Chrome Moly Vanadium. This steel is known for its strength, durability, and resistance to heat.
- Magazine Included: No. Magazines must be purchased separately.
Performance & Functionality
The CMMG Dissent Mk4 .22 ARC 16.1 Upper Group performs admirably, providing reliable function and good accuracy. The direct impingement system is well-tuned. I found it to cycle reliably with a variety of .22 ARC ammunition. Accuracy is excellent. I was able to consistently achieve sub-MOA groups at 50 yards with quality ammunition.
The side-charging handle is a significant advantage, allowing for quick and easy bolt manipulation without disrupting your sight picture. The only weakness I observed was its sensitivity to ammunition. Some brands of .22 ARC ammunition produced more failures to extract than others. Overall, it meets and exceeds expectations for a dedicated .22 ARC upper.
Design & Ergonomics
The build quality is excellent. The aluminum receiver feels solid and well-machined. The fit and finish are top-notch. The M-LOK handguard is comfortable to hold. The overall weight of 5.05 lbs is well-balanced on an AR-15 lower receiver.
The side-charging handle and the absence of a buffer tube contribute to a more compact and ergonomic platform. The CMMG Dissent Mk4 .22 ARC 16.1 Upper Group is incredibly user-friendly. The controls are intuitive, and the side-charging handle is easy to operate even with gloved hands. The ergonomics lend themselves well to both right- and left-handed shooters.
Durability & Maintenance
The CMMG Dissent Mk4 .22 ARC 16.1 Upper Group appears to be built to last. The aluminum receiver and 4140 Chrome Moly Vanadium barrel are durable and should withstand years of use. Maintenance is simple. The bolt is easily accessible for cleaning, and the direct impingement system is straightforward to maintain.
Occasional cleaning and lubrication are all that is needed to keep it running smoothly. The absence of a buffer tube simplifies disassembly and cleaning. The robust construction and easy maintenance suggest that this upper will last for many years.
Accessories and Customization Options
The CMMG Dissent Mk4 .22 ARC 16.1 Upper Group includes a 1913 Picatinny rail end plate, allowing the user to attach slings or folding stocks. The M-LOK handguard provides ample space for accessories. This allows for the addition of lights, lasers, or vertical grips.
The upper receiver is compatible with any standard mil-spec AR-15 lower receiver. This opens up a wide range of customization options, including different triggers, grips, and stocks. The 1/2×28 threaded barrel allows for the use of suppressors or other muzzle devices. The Dissent upper is also compatible with various AR-15 optics.
Pros and Cons of CMMG Dissent Mk4 .22 ARC 16.1 Upper Group
Pros
- Compact and lightweight design due to the absence of a buffer tube.
- Excellent accuracy with quality .22 ARC ammunition.
- Convenient side-charging handle for quick and easy bolt manipulation.
- Reliable direct impingement system for consistent cycling.
- Easy to maintain and clean.
Cons
- Relatively expensive compared to .22 LR AR conversion kits.
- Ammunition sensitivity; some .22 ARC brands may cause more malfunctions.
Who Should Buy CMMG Dissent Mk4 .22 ARC 16.1 Upper Group?
The CMMG Dissent Mk4 .22 ARC 16.1 Upper Group is perfect for shooters looking for a dedicated .22 ARC AR platform with improved accuracy and longer range than traditional .22 LR conversions. It is also great for those seeking a compact and lightweight AR-15 upper receiver. This makes it suitable for training, small game hunting, or recreational shooting.
Those who should skip this product are shooters who are primarily concerned with cost. .22 LR AR conversion kits offer a more affordable entry point into the world of rimfire ARs. Individuals who don’t plan on shooting past 100 yards may not need the improved ballistics of the .22 ARC.
Must-have accessories or modifications include a quality optic (red dot or scope) for maximizing accuracy. .22 ARC magazines are essential. A lightweight and adjustable stock is recommended for optimal comfort and ergonomics.
Conclusion on CMMG Dissent Mk4 .22 ARC 16.1 Upper Group
The CMMG Dissent Mk4 .22 ARC 16.1 Upper Group is a well-engineered and high-performing upper receiver. It offers a unique combination of compact design, reliable function, and excellent accuracy. While the price is higher than some alternatives, the performance and features justify the cost.
The value proposition is strong for shooters who prioritize quality, accuracy, and a compact form factor. I would personally recommend it to anyone looking for a top-tier .22 ARC AR platform.
If you are looking for a dedicated .22 ARC upper receiver that offers excellent performance and a unique shooting experience, the CMMG Dissent Mk4 .22 ARC 16.1 Upper Group is definitely worth considering. Upgrade your AR-15 today and experience the CMMG difference!