The Guntec USA Extreme Duty castle nut is a wide castle nut for AR-15 buffer tubes with an enhanced design for extra strength and durability. It fits both mil-spec and commercial buffer tubes. Made from steel with a nitride finish in the USA.
- Brand: Guntec USA
- Type: Extreme Duty wide castle nut
- Fits: Mil-spec and commercial AR-15 buffer tubes
- Material: Steel
- Finish: Nitride
- Made in USA
- Manufacturer part number: CASTLE-EXD
