Fortis Manufacturing AR-15 Standard Castle Nut
Fortis Manufacturing, Inc.
$11.69
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Fortis Manufacturing, Inc.
Fortis Manufacturing AR-15 Standard Castle Nut
The Fortis Standard Castle Nut is a precision-machined, lightweight upgrade for any AR-15 build, delivering the strength and reliability you need without the unnecessary bulk of a standard steel castle nut.
- Machined from solid billet 7075-T6 aircraft-grade aluminum for maximum strength
- Weighs just 0.2 oz — a significant reduction over traditional steel castle nuts
- Compatible with all mil-spec buffer tubes for broad fitment across AR-15 platforms
- Type III hardcoat anodized finish resists wear, corrosion, and hard use
- Installs easily using any standard AR stock wrench — no special tools needed
- Proudly designed and manufactured in the USA by Fortis Manufacturing
Who This Is For
The Fortis Standard Castle Nut is ideal for weight-conscious AR-15 builders — competitive shooters, hunters, and enthusiasts who are counting every ounce on a lightweight build without compromising fit, finish, or long-term durability. It's also a sharp-looking upgrade for anyone who wants a more refined, purpose-built aesthetic on their mil-spec buffer tube assembly.
Specifications
| Brand | Fortis Manufacturing, Inc. |
|---|---|
| Material | 7075-T6 Billet Aircraft-Grade Aluminum |
| Weight | 0.2 oz |
| Finish | Type III Hardcoat Anodize |
| Compatibility | Mil-Spec Buffer Tubes |
| Installation Tool | Standard AR Stock Wrench |
| Country of Origin | Made in the USA |
Frequently Asked Questions
Will the Fortis Standard Castle Nut fit my AR-15 buffer tube?
Yes. The Fortis Standard Castle Nut is designed to fit all mil-spec diameter buffer tubes, which are the most common standard used across AR-15 and M16-pattern rifles. If you are unsure whether your buffer tube is mil-spec or commercial-spec, check the tube's diameter — mil-spec tubes measure approximately 1.14 inches in outer diameter, while commercial tubes measure slightly larger at approximately 1.17 inches. This castle nut is intended for mil-spec tubes only.
Is an aluminum castle nut as durable as a steel one?
When machined from 7075-T6 aluminum — the same alloy used in aerospace and defense applications — and finished with a Type III hardcoat anodize, an aluminum castle nut offers excellent durability for standard AR-15 use. While steel is technically harder, the weight savings (often over 80% lighter than steel) make aluminum castle nuts a popular choice for competition and lightweight builds where the nut experiences no direct impact forces during normal operation.
Do I need any special tools to install the Fortis Castle Nut?
No special tools are required. The Fortis Standard Castle Nut installs using any standard AR-15 stock or castle nut wrench, which is a common and inexpensive tool found in most AR armorers' kits. After installation, the nut should be properly staked or secured to the end plate to prevent backing out during use — this is standard practice regardless of the castle nut brand or material.
