CMMG - 10.4" Barrel for FN PS90, 4140CM SBN, 5.7x28mm

Using a 10.4-inch barrel on the FN PS90 allows for a more compact firearm configuration, ideal for close-quarters scenarios. This shorter barrel length is particularly beneficial in urban environments or for tactical applications where maneuverability is crucial. However, it's important to note that shortening the barrel can affect the velocity and range of the 5.7x28mm round, potentially reducing its effective range compared to a longer barrel.

The 4140CM steel with Salt Bath Nitride (SBN) finish enhances the barrel's durability and resistance to corrosion. This combination ensures that the barrel can withstand the stresses of repeated firing and environmental exposure, making it a reliable choice for long-term use. The SBN finish also provides a smoother surface, which can improve the overall lifespan of the barrel by reducing friction and wear.

The 1:9 twist rate is specifically designed to stabilize the 5.7x28mm caliber projectiles for improved accuracy. This twist rate is optimal for the bullet weight and velocity of the 5.7x28mm, ensuring that the rounds maintain a stable flight path. For shooters, this means more consistent shot placement and better performance at various distances.

The CMMG 10.4-inch barrel is specifically designed for the FN PS90 platform, making it unsuitable for other firearms without significant modifications. Its unique specifications, such as the M12x1LH muzzle threads and the 5.7x28mm caliber, are tailored to the PS90's design. Attempting to fit this barrel onto a different firearm could result in compatibility issues and is not recommended.

The M12x1LH threads on the CMMG 10.4-inch barrel allow for the attachment of specific muzzle devices such as the P90 Style Flash Hider. Additionally, CMMG offers an M12x1LH to 1/2x28 Thread Adapter, which expands the range of compatible muzzle devices. This flexibility enables users to customize their PS90 setup according to their tactical needs or personal preferences.

Converting the FN PS90 to a Short Barrel Rifle (SBR) changes its classification under U.S. federal law, requiring additional legal steps. Owners must file an ATF Form 1 and receive approval before making the conversion. This process includes paying a tax stamp and undergoing a background check. It's crucial to comply with all legal requirements to avoid serious penalties.

The CMMG 10.4-inch barrel weighs approximately 2 pounds, which impacts the overall balance and handling of the FN PS90. While the shorter barrel contributes to a more compact and agile firearm, the weight distribution may feel different compared to the original setup. Users should practice handling the modified PS90 to become accustomed to its new dynamics, especially in rapid-fire scenarios.

When installing the CMMG 10.4-inch barrel, accessories such as the P90 Style Flash Hider and the M12x1LH to 1/2x28 Thread Adapter are recommended. These components enhance the barrel's functionality and allow for greater customization. Additionally, investing in a quality optic can improve targeting precision, especially given the shorter sight radius of the SBR configuration.

The Lifetime Quality Guarantee from CMMG provides peace of mind by ensuring that the barrel is free from manufacturing defects. This guarantee means that if any issues arise due to workmanship, CMMG will address them, potentially saving owners from costly repairs or replacements. It's a testament to the company's confidence in their product's durability and performance.

When selecting ammunition for the CMMG 10.4-inch barrel, it's important to choose rounds that are compatible with the 5.7x28mm caliber and optimized for shorter barrels. Ammunition designed for higher velocity may not perform as expected due to the reduced barrel length, potentially affecting accuracy and terminal performance. Testing different loads can help identify the best option for your specific setup and intended use.