• 1 x Fortis K2 Castle Nut System (RED)

The Fortis K2 Locking Castle Nut system helps keep your buffer tube secure and stylish!


  • 7075 T6 Aluminum
  • Light Weight 0.53oz
  • Not set screws or staking required
  • Made in USA!

Locking the castle nut eliminates the need to “stake” or lock in your system and greatly reduces the chances of your buffer tube coming loose over time.

Used in Our Custom Builds

Our custom builds prominently feature red accents. The red castle nut adds just a subtle hint of red without going overboard!

How to Install?

Install just like any ordinary castle nut, however once it starts to get hand tight, just go 1 – 2 clicks in from there and you should be good.

You can check your buffer tube to see if there is any wiggle / play. If there is, you can try to go one more click.

Note: If you want the best results, always ensure that the locking system actually “clicks” into place on the final turn. If you are between clicks, the castle nut may loosen back one “click”.

Weight 3 oz
Dimensions 6 × 4 × 1 in

H1, H2, H3