The CMMG ENDEAVOR MK3 UPPER GROUP 308 Win 20 Black Made a Bold First Impression
The CMMG ENDEAVOR MK3 UPPER GROUP 308 Win 20 Black arrived looking like it meant business. This isn’t your budget build; it’s a serious piece of kit from a reputable manufacturer, CMMG, known for quality AR components. The promise of .308 Winchester power in a relatively maneuverable package piqued my interest immediately.
I’d been searching for an upper receiver group that could pull double duty: accurate enough for medium-range target work and powerful enough for ethical hunting in areas with larger game. My current AR-15 was great, but lacked the range and punch for certain scenarios. The CMMG seemed to bridge that gap.
Unboxing was a pleasant experience. The fit and finish were immediately impressive, and the weight, while substantial, felt balanced. The black Cerakote finish appeared durable and evenly applied. Compared to a similar upper from Aero Precision I considered, the CMMG felt more robust and well-appointed, justifying the price difference. A less expensive option from a budget brand felt flimsy in comparison.
I was excited. This CMMG ENDEAVOR MK3 UPPER GROUP 308 Win 20 Black seemed like a significant step up and a potentially perfect fit for my needs, provided it delivered on its promise at the range.
Real-World Testing: Putting CMMG ENDEAVOR MK3 UPPER GROUP 308 Win 20 Black to the Test
First Use Experience
My first outing with the CMMG ENDEAVOR MK3 UPPER GROUP 308 Win 20 Black was at my local shooting range. I paired it with a lower receiver I’d assembled previously. Conditions were ideal: clear skies and moderate temperatures.
The CMMG proved easy to use right out of the box. After a quick bore sight, I was printing respectable groups at 100 yards within the first few magazines. The recoil was more substantial than a .223, as expected, but manageable. I did experience one failure to extract in the first 20 rounds, but it vanished as the system broke in.
Extended Use & Reliability
After several months of regular use, the CMMG ENDEAVOR MK3 UPPER GROUP 308 Win 20 Black has proven to be reliable. I’ve run several hundred rounds through it, including a variety of bullet weights and brands, with only the initial hiccup.
The Cerakote finish has held up remarkably well, showing no signs of wear despite being bumped around in rifle cases. Cleaning is straightforward. Standard AR cleaning procedures apply. Compared to some of my previous AR builds, the CMMG feels like it requires less frequent cleaning to maintain optimal performance.
Breaking Down the Features of CMMG ENDEAVOR MK3 UPPER GROUP 308 Win 20 Black
Specifications
- Caliber: .308 Winchester. This is a powerful and versatile cartridge suitable for hunting medium to large game and engaging targets at extended ranges.
- Weight: 6.0 lbs. This is a significant weight, but manageable considering the caliber and barrel length; it provides a stable shooting platform.
- Barrel Length: 20 inches. The longer barrel helps maximize velocity and accuracy, making it suitable for longer-range engagements.
- Barrel Twist: 1:10. This twist rate is optimal for stabilizing a wide range of .308 bullet weights.
- Barrel Contour: MT (Medium Taper). The Medium Taper strikes a good balance between weight and rigidity for accuracy.
- Barrel Material: 416SS SBN (Salt Bath Nitride). The stainless steel construction provides excellent corrosion resistance, while the SBN treatment enhances surface hardness and durability.
- Muzzle Device: CMMG ZEROED Muzzle Brake. The muzzle brake helps reduce recoil and muzzle rise, improving control and follow-up shots.
- Muzzle Thread: 5/8 x 24. This is a standard thread pitch for .308 barrels, allowing compatibility with a wide range of muzzle devices and suppressors.
- Gas Port Location: Rifle. The rifle-length gas system provides smoother recoil impulse and reduced wear on the components compared to shorter gas systems.
- Gas Block: 0.750 Non-Adjustable. The 0.750″ diameter gas block is a standard size, and the non-adjustable design simplifies the system.
- Upper Receiver: Billet 7075 T6 Aluminum. The billet construction and high-strength aluminum provide excellent rigidity and durability.
- Hand Guard: CMMG EML15 M-LOK. The 15-inch handguard provides ample space for mounting accessories and a comfortable grip.
- Finish: Cerakote Standard. The Cerakote finish is durable and provides excellent corrosion resistance.
- Charging Handle: CMMG ZEROED Ambi. The ambidextrous charging handle allows for easy operation by both left- and right-handed shooters.
- Length: 30.2 inches. This length provides a good balance between accuracy and maneuverability.
- Operating System: Direct Impingement. The Direct Impingement system is a proven and reliable design.
Performance & Functionality
The CMMG ENDEAVOR MK3 UPPER GROUP 308 Win 20 Black performs admirably. Accuracy is excellent, easily achieving sub-MOA groups with match-grade ammunition. The rifle-length gas system provides a smooth and manageable recoil impulse. Reliability has been solid after the initial break-in.
The muzzle brake is effective at reducing recoil, but it is loud.
Design & Ergonomics
The build quality is top-notch. The materials used are high-quality, and the fit and finish are excellent. The weight is substantial, but balanced, making it comfortable to shoot from various positions. The ambidextrous charging handle is a welcome feature.
There is minimal learning curve. It feels like a well-refined AR-15 platform.
Durability & Maintenance
The CMMG ENDEAVOR MK3 UPPER GROUP 308 Win 20 Black is built to last. The high-quality materials and durable finish suggest it will withstand years of use. Maintenance is straightforward. Regular cleaning and lubrication are all that’s required.
Accessories and Customization Options
The CMMG ENDEAVOR MK3 UPPER GROUP 308 Win 20 Black comes with the ZEROED .308 Ambi Charging Handle, ZEROED Mk3 Polymer Dust Cover, and ZEROED Muzzle Brake .308. The M-LOK handguard provides ample space for mounting accessories such as optics, lights, and forward grips. The upper is compatible with any standard LR-308/DPMS Gen 1 High-Pattern lower receiver. I found that Magpul .308 magazines fed reliably.
Pros and Cons of CMMG ENDEAVOR MK3 UPPER GROUP 308 Win 20 Black
Pros
- Excellent accuracy and long-range performance due to the 20″ barrel.
- High-quality components and durable construction ensure longevity.
- Rifle-length gas system provides smooth recoil impulse.
- Ambidextrous charging handle enhances usability for all shooters.
- M-LOK handguard offers plenty of space for accessory mounting.
Cons
- The 6.0 lb weight may be a drawback for those prioritizing lightweight builds.
- The CMMG ZEROED Muzzle Brake is effective, but significantly increases noise.
Who Should Buy CMMG ENDEAVOR MK3 UPPER GROUP 308 Win 20 Black?
The CMMG ENDEAVOR MK3 UPPER GROUP 308 Win 20 Black is perfect for hunters needing a reliable and accurate .308 platform. It also excels as a target or competition rifle where long-range accuracy is paramount. It is well-suited for anyone wanting a high-quality, durable AR-10 style rifle.
Those prioritizing a lightweight rifle or strictly needing a close-quarters weapon should skip this product. The longer barrel and heavier weight make it less ideal for tight spaces.
A quality optic is a must-have accessory to truly utilize the long-range capabilities of this upper. A bipod or shooting rest is also recommended for optimal accuracy.
Conclusion on CMMG ENDEAVOR MK3 UPPER GROUP 308 Win 20 Black
The CMMG ENDEAVOR MK3 UPPER GROUP 308 Win 20 Black is an outstanding upper receiver group that delivers exceptional accuracy, reliability, and durability. The price of $1,014.99 is justified given the quality of components and performance. I would wholeheartedly recommend this upper to anyone looking for a serious .308 AR platform.
If you are looking for a top-tier AR-10 build that will perform, then the CMMG ENDEAVOR MK3 UPPER GROUP 308 Win 20 Black should be at the top of your list. Upgrade your rifle today.