The CMMG Receiver Extension Castle Nut MK4 is a replacement castle nut designed for use with AR-15 and MK4 carbine receiver extensions. Its matte black finish offers durability, and it is compatible with a range of AR platforms where a castle nut is required.
Matte black finish for durability and corrosion resistance
Compatible with AR-15 and MK4 carbine receiver extension tubes
Designed as a castle nut for buffer tube installation
This component is suitable for maintaining or assembling AR-15 and MK4 platforms, ensuring secure buffer tube retention and reliable function.