Armaspec Self Retention Castle Nut AR-15 FDE

Armaspec's castle nut removes the worst part of a buffer tube install: staking. The thread geometry locks the nut against the end plate and holds it there under recoil, so there is no punch work on a finished receiver and no thread locker to break loose later if the stock has to come off.

It is machined from aluminum, which drops a little weight off the back of the rifle, and finished in Flat Dark Earth for anyone building around an FDE stock and grip instead of another all black carbine. Standard AR-15 receiver extension threads mean it works with mil-spec tubes and common end plates. Armaspec covers it with a lifetime warranty.