Forward Controls Design 4140 Billet Castle Nut


The original MIL-SPEC castle nut is a hard product to improve upon, but Forward Controls Design has proven it is not impossible. The CNF is based on the original technical data package specification for the castle nut but does offer several improvements. Deeper staking notches make for much more secure staking. Even installation is improved with the coarse serrations making threading it down to the endplate easier and more comfortable.

(11 customer reviews)

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  • 4140 PH Steel construction
  • Black Nitride
  • Tough Flat Dark Earth Cerakote finish
  • Tough OD Green Cerakote finish
  • 25% longer staking notches
  • Additional notch added
  • Coarse serrations for easy installation

Military specifications require castle nuts to be staked in two locations to ensure the castle nut and buffer tube will not loosen without deliberate action, and FCD believes this is one of those points where less is definitely not more. Traditional MIL-SPEC castle nuts have 3 staking notches, the CNF features 4, ensuring at any time three are available to be used. Each notch has also been upgraded to a deep, 30-degree cut, making them 25% longer than MIL-SPEC to ensure enough material can be staked into the notch for secure installation. To make threading the castle against the end plate even easier, the outer edge features coarse serrations.

Forward Controls Design firmly believes in the elegance of simplicity. Not content to produce purely aesthetic components, they put function before form to create parts and accessories that actually improve the handling and function of your firearms. When you need parts that just work without complication, you need Forward Controls Design.

Additional information

Weight 0.0375 lbs
Dimensions 5 × 1 × 4 in

Black, FDE, OD Green, Burnt Bronze

11 reviews for Forward Controls Design 4140 Billet Castle Nut

  1. Christopher Rausch (verified owner)

    Works as it should and looks good doing it. Stake it.

  2. Andy S (verified owner)

    Looks awesome, works great.

  3. dustinsingley (verified owner)

    Looks great and works great. Stake your nuts

  4. dakotapritchard (verified owner)

    We’ll made and finished. Typical FCD. Stake your castle nuts.

  5. Nathan Serna (verified owner)

    Well made and well coated. Eventually will upgrade my other rifles with FCD small parts.

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