CMMG 90CA9B4 Buffer Assembly Carb MK9 - Upgrade AR-15 enhances the reliability and performance of your AR-15 or M4 chambered in 9mm Luger. Designed for compatibility with carbine receiver extensions, this buffer assembly ensures optimal cycling and reduced recoil. Upgrade your firearm with this durable component, crafted to meet high-performance standards. Fits AR-15 rifles chambered in 9mm Luger/CMMG MK9 or similar pattern variant using a carbine receiver extension Elevate your shooting experience with the precision-engineered CMMG Buffer Assembly.