The Guntec USA AR15 Castle Nut, CAR/M4, Mil-Spec (brand part number CASTLE) secures a mil-spec buffer tube to an AR15 receiver extension. Machined from steel by Guntec USA and finished with a durable Nitride coating in black, it is made in the USA and sized to CAR/M4-pattern specifications for a correct factory fit. It is a simple, inexpensive part for a build or a replacement for a lost or damaged castle nut.

Key Specifications

• Mil-spec castle nut for CAR/M4-pattern buffer tubes.
• Machined from steel.
• Finished with a Nitride coating for corrosion resistance.
• Finished in black.
• Made in the USA.

Frequently Asked Questions

What buffer tubes does this nut fit? CAR/M4-pattern mil-spec buffer tubes.

What is it made from? Steel with a Nitride finish for corrosion resistance.

Buy the Guntec USA AR15 Castle Nut, CAR/M4, Mil-Spec

Complete your build with a part from our gun parts kits selection. Order it from our Lubbock, Texas gun shop for fast, insured shipping.