At the risk of being too forward, Brownells Gun Tech™ Caleb Savant wants to talk to us about something kinda personal: the AR-15 castle nut. Specifically, the Forward Controls Design CNF Castle Nut. Small parts can make the difference between an OK rifle and a great one. The castle nut may seem like an inconsequential little part, but it locks the receiver extension (aka "buffer tube") to the lower receiver. The buffer has to move smoothly in that tube for your rifle to cycle reliably. And what attaches to the buffer tube? Oh yeah, the stock! Caleb doesn't beat around the bush here. He thinks the "Castle Nut, FCD" is the BEST AR-15 castle nut ever made. Swell, but how is it different from an ordinary mil-spec castle nut?
The CNF is machined from 4140 carbon steel billet and Nitride-finished, rather than Parkerized. The castle nut is one part on the AR-15 that does sometimes rust, and the Nitride finish protects against corrosion far better than the traditional phosphate finish. The CNF's staking notches are deeper and have a 30-degree angle that helps you more securely stake it to the receiver endplate so it can't back out. You do always stake your castle nuts, don't you?
How do other folks at the range know your new AR is rockin' the Forward Controls Design CNF castle nut? Aside from that gloss Nitride finish, the CNF has dimples between the wrench notches at the rear. As we all know, dimples are cute! The also give your fingers get extra purchase when you thread the CNF toward the endplate.
