Sons of Liberty Gun Works M4-89 .300 AAC Blackout Upper Receiver Review

The Story Behind the Sons of Liberty Gun Works M4-89 .300 AAC Blackout Half Complete Upper Receiver

The Sons of Liberty Gun Works M4-89 .300 AAC Blackout Half Complete Upper Receiver represents a significant step up for those looking to build or upgrade their AR platform. This half complete upper receiver, chambered in the versatile .300 AAC Blackout, offers a blend of quality craftsmanship and tactical functionality that sets it apart. Sons of Liberty Gun Works (SOLGW) has built a reputation for producing durable and reliable components, and this upper receiver promises to deliver on that legacy.

I’ve spent years building and modifying AR-platform rifles, searching for that perfect balance of performance and reliability. I was specifically looking for a .300 Blackout upper receiver that could handle both supersonic and subsonic rounds with equal aplomb, and also be compact and maneuverable. The SOLGW M4-89 seemed to fit the bill perfectly.

Upon unboxing, the first thing that struck me was the robust build quality. The finish was flawless, and every component felt solid and well-machined. It felt significantly more substantial than some of the cheaper options I’ve handled.

Compared to similar offerings from Aero Precision and Bravo Company Manufacturing (BCM), the SOLGW M4-89 stood out due to its attention to detail and no-nonsense design. While Aero offers value and BCM is known for its reliability, the SOLGW seemed to offer a level of craftsmanship that combined the best of both worlds. I chose the SOLGW because I was prioritizing reliability and a precise gas system for optimal .300 Blackout performance.

My initial impression was excitement mixed with a healthy dose of anticipation. This upper receiver looked and felt like a quality piece of equipment. I couldn’t wait to get it to the range.

Real-World Testing: Putting Sons of Liberty Gun Works M4-89 .300 AAC Blackout Half Complete Upper Receiver to the Test

First Use Experience

My initial testing took place at a local outdoor range, under typical Texas conditions: hot and dusty. I paired the Sons of Liberty Gun Works M4-89 .300 AAC Blackout Half Complete Upper Receiver with a reliable lower receiver and a variety of .300 Blackout ammunition, including both supersonic and subsonic loads. The goal was to assess its reliability, accuracy, and overall handling.

The upper performed admirably in the dusty conditions. There were no malfunctions during the first range session. The rifle cycled both supersonic and subsonic ammunition smoothly, demonstrating excellent gas regulation.

The SOLGW required no break-in period; it ran flawlessly right out of the box. One pleasant surprise was how well the included handguard protected my hand from heat, even after extended firing sessions.

Extended Use & Reliability

After several months of consistent use, the Sons of Liberty Gun Works M4-89 .300 AAC Blackout Half Complete Upper Receiver continues to impress. It has seen action in various conditions, including a few rainy days and a weekend survival course in the woods. The rifle has remained reliable and accurate throughout.

The finish has proven to be incredibly durable, showing minimal signs of wear and tear despite being subjected to rough handling and exposure to the elements. Cleaning and maintenance are straightforward. Standard AR cleaning procedures are sufficient to keep the upper receiver in top condition.

In comparison to my previous .300 Blackout upper receiver from a different manufacturer, the SOLGW has significantly outperformed it in terms of reliability and accuracy. The gas system appears to be tuned perfectly. This ensures consistent cycling with a wider range of ammunition.

Breaking Down the Features of Sons of Liberty Gun Works M4-89 .300 AAC Blackout Half Complete Upper Receiver

Specifications

The Sons of Liberty Gun Works M4-89 .300 AAC Blackout Half Complete Upper Receiver boasts impressive specifications. It is chambered in .300 AAC Blackout, offering versatility in both supersonic and subsonic applications. The overall length is 13.9 inches, while the barrel length is 13 inches, providing a compact and maneuverable platform.

The upper receiver is finished in a durable black coating, offering excellent corrosion resistance. It features a 13-inch handguard length, providing ample space for accessories. Designed for the AR Platform, it’s compatible with most standard AR-15 lower receivers.

• Caliber: .300 AAC Blackout – This offers versatility for both subsonic suppressed and supersonic unsuppressed use.
• Barrel Length: 13 inches – A shorter barrel is ideal for maneuverability and home defense applications.
• Handguard Length: 13 inches – This provides ample rail space for accessories like lights, lasers, and foregrips.

It’s important to note that the Bolt Carrier Group (BCG) and Charging Handle are NOT included. This allows users to select their preferred components based on their specific needs and budget. A magazine is also not included, as is standard with upper receivers.

Performance & Functionality

The Sons of Liberty Gun Works M4-89 .300 AAC Blackout Half Complete Upper Receiver excels in performance and functionality. The gas system is finely tuned. This ensures reliable cycling with a wide range of .300 Blackout ammunition.

The upper receiver is incredibly accurate, easily achieving sub-MOA groups with quality ammunition and a competent shooter. Its main strength is its reliability and smooth operation, making it a dependable choice for any application. No significant weaknesses have been observed during testing.

The SOLGW M4-89 has exceeded my expectations in terms of both accuracy and reliability.

Design & Ergonomics

The build quality of the Sons of Liberty Gun Works M4-89 .300 AAC Blackout Half Complete Upper Receiver is exceptional. High-quality materials and precise machining are evident throughout. The upper receiver feels solid and well-balanced, inspiring confidence in its durability.

The design is user-friendly. There is minimal learning curve for experienced AR-15 users. The handguard provides a comfortable and secure grip, even with wet or gloved hands.

Durability & Maintenance

The Sons of Liberty Gun Works M4-89 .300 AAC Blackout Half Complete Upper Receiver is built to last. The durable finish and high-quality components ensure long-term reliability. Maintenance is simple. Standard AR-15 cleaning procedures are sufficient.

Accessories and Customization Options

While the Sons of Liberty Gun Works M4-89 .300 AAC Blackout Half Complete Upper Receiver is a “half complete” receiver, it does not include any accessories beyond the assembled upper and handguard. However, the 13-inch handguard provides ample space for mounting various accessories. It readily accepts popular accessories from brands like Magpul, Streamlight, and EOTech.

The absence of a BCG and charging handle allows for full customization. Users can select components that best suit their needs and preferences. This provides unparalleled flexibility.

Pros and Cons of Sons of Liberty Gun Works M4-89 .300 AAC Blackout Half Complete Upper Receiver

Pros

• Exceptional Reliability: Cycles both supersonic and subsonic ammunition flawlessly.
• Superb Accuracy: Consistently achieves sub-MOA groups with quality ammunition.
• Durable Construction: Built with high-quality materials and a robust finish.
• Customization Options: Allows users to select their preferred BCG and charging handle.
• Compact and Maneuverable: The 13-inch barrel and handguard make it ideal for tight spaces.

Cons

• BCG and Charging Handle Not Included: Requires additional purchase.
• Price: Higher price point compared to some competitors.

Who Should Buy Sons of Liberty Gun Works M4-89 .300 AAC Blackout Half Complete Upper Receiver?