Forward Controls Design CNF Castle Nut


Flat Dark Earth (FDE)
Burnt Bronze
OD Green

Product Description

From the Manufacturer:

Call us old-fashioned, we like our castle nut staked to prevent it from rotating loose on the receiver extension and causing malfunctions. Army manual calls for the castle nut to be torqued to 38 to 42ft/lb, and staked in two places. While we’re not in the “more is better, bigger is better” camp, there are times less isn’t more.

The TDP spec castle nut is a simple and robust fastener that is almost perfect for the job it’s tasked to perform. Over the years, FCD has consistently come up with two minor gripes, first is its staking notches seem rather shallow and short, second is many don’t enjoy using the castle nut’s wrench notches as serrations (fingers invariably find their way to these sharp cutouts) to rotate it towards to the endplate while installing it.

CNF (Castle Nut, Forward Controls) is based on the TDP spec castle nut, with a couple of changes:

  • Staking notches angle changed from 45 to 30 degrees, this results in longer (25% longer than TDP spec) and deeper notches than found on TDP castle nuts.
  • Number of staking notches increased from 3 to 4, spaced equally on the CNF. The castle nut is to be staked in two places, we’re not advocating staking in more than two places, CNF’s 4 staking notches mean that, at all times, 3 will be visible and available for staking, it simply gives the user more staking location options.
  • Coarse serrations on the wrench side of the nut, a single-use feature to make it easier while rotating the CNF towards the endplate.

It is FCD’s opinion that a castle nut should be staked per TM, CNF’s longer and deeper notch reinforces the belief, that once installed and staked, it will not loosen without the user’s deliberate action. They love the idea of quick detach, but some things on an AR are meant to stay put, and considerable effort was made to ensure that by the original designers. CNF is a continuation and evolution in that direction.

CNF is billet machined in 4140 PH steel, and black nitrided (Cerakoted FDE, OD green, and burnt bronze also available). As with everything Forward Controls Design produces, it is proudly made in the USA.




Technical Information

Finish Nitride
Firearm Compatibility ,
Material Steel

Catalog Location

California Prop 65 Warning

WARNING: This product can expose you to chemicals, which are known to the State of California to cause Cancer and Reproductive Harm. For more information visit

Customer Reviews

Based on 6 reviews
Fit great

Delivered on time and fit great. Color was exactly what I was looking for

R E.
Great addition to my budget build!

Thank you for the fast shipping!

joseph h.

You guyz are great with super fast shipping and good prices! Thankz and I'll totally order from here again!

joshua l.
The only castle nut I'll buy

Quite honestly the finish and the fit of this castle nut is far superior to any castle that I've used in the past. Fast shipping. I put one on all of my builds. Will buy again.

Shane L.
Castle nut

Good FDE color. Stays tight. No issues.