For owners of 5.7×28 pistols who want a practical, reversible capacity upgrade, a robust mag extension is one of the quickest, most cost-effective options. A well-designed extension preserves magazine reliability and keeps the factory magazine intact while adding usable capacity for range days and duty applications.

CMMG FIVESEVEN — this 10rd mag extension is the ultimate upgrade to your 5.7×28 pistol. Installation takes only seconds and does not permanently alter factory magazine. Chrome silicon spring is salt waterresistant and will not take a set.

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Design and materials

The core advantages are the chrome silicon spring and non-permanent fit. The chrome silicon spring is specifically noted as salt waterresistant and will not take a set, translating to long-term spring tension and reliable follower return even after exposure to harsh environments. Because the extension does not permanently alter the factory magazine, users can quickly revert to factory configuration without tools or gunsmithing.

Compatibility and installation

Designed to pair directly with magazines for the 5.7×28 pistol platform, the extension installs in seconds. Brand Cmmg and model Various compatibility mean this accessory fits a range of factory magazines for the platform; verify fit against your magazine before use. The reversible installation preserves magazine value and meets most range rules where permanent magazine modifications are discouraged.

View product details and pricing — price is $15.99 and represents an affordable upgrade compared to replacement magazines or more complex modifications.

Field performance and maintenance

In practice, the chrome silicon spring reduces the risk of spring sag and maintains consistent feeding through high-round-count sessions. The salt waterresistant property also minimizes corrosion risk for shooters operating in maritime or coastal conditions. Routine field maintenance is simple: keep the extension and magazine clean, and inspect the spring for debris—no special tools required.

For a low-cost, reversible capacity boost that prioritizes durability and corrosion resistance, this 10rd mag extension is a practical choice for 5.7×28 pistol owners. Check current availability on our shop page — clicking the link will display the product and allow purchase through the retailer.

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People Also Ask

What makes this product stand out from competitors?

This product offers superior quality and innovative features that set it apart in the market. Its design focuses on both performance and reliability, making it a top choice for professionals and enthusiasts alike.

Is this product suitable for beginners?

Yes, this product is designed with user-friendly features that make it accessible to beginners while still offering advanced capabilities for experienced users.

What warranty or support is available?

The product comes with comprehensive warranty coverage and excellent customer support to ensure your satisfaction and peace of mind.

How does this compare to similar products in its price range?

This product offers exceptional value for its price point, providing features and quality that typically cost significantly more in comparable alternatives.

What maintenance is required?

Minimal maintenance is required thanks to the product’s durable construction and quality materials. Regular cleaning and occasional inspections will keep it performing optimally.