The AR-15 castle nut is a crucial component of any AR15/AR10 build. The caste nut is used to secure a receiver extension (buffer tube) to the lower receiver. Made from 4140 steel and finished in a durable manganese phosphate coating for years of reliable service.

A castle nut is an essential part of your next rifle or pistol build. Don’t forget to pick one up when you’re buying a new buffer tube or buffer kit to complete your next build. We also have parts kits available to help finish your build, or just to have one hand for spares.