The Castle Nut is a lock nut designed to secure the buffer tube of your AR-15 stock.

This lightweight yet strong castle nut is made from carbon fiber-reinforced polymer, making it an ideal alternative when metal castle nuts are hard to find.

We developed these out of necessity, and in our tests, they performed exceptionally well. They have proven to be a reliable solution.
These castle nuts have already been successfully used on several FX DRS Tactical air rifles.

Do note: As these nuts are made of polymer, we do not recommend using them for firearms.