CMMG 9MM Ejection Port Cover Kit – AR-15 9mm Conversions

The CMMG 9MM Ejection Port Cover Kit is a purpose-built replacement for AR-15 platform firearms chambered in 9mm. Standard AR ejection port covers are sized for .223/5.56 cases; this kit features a modified cover opening optimized for 9mm case geometry, reducing the chance of case rim interference during ejection and improving reliability in pistol-caliber carbine builds.

Constructed from mil-spec materials with a durable black finish. Installation is straightforward for anyone familiar with AR-15 assembly—requires only a roll pin punch and basic tools. The kit includes the modified door, C-clip, spring, and roll pin for a complete replacement.

• Part Type: Ejection Port Cover Assembly
• Compatible Firearms: AR-15 chambered in 9mm
• Material: Mil-spec steel
• Finish: Black
• Installation: Drop-in with basic tools
• Includes: Modified ejection port door, C-clip, spring, roll pin