Ergo Castle Nut for AR-15 - Secure Your AR Build with Precision in Black - 4971-(B)
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Ergo Grips
Overview
The Ergo Castle Nut for AR-15 is a precision-engineered component designed to securely fasten the buffer tube to the lower receiver, ensuring stability in your build. Made from durable steel and finished in black, this castle nut provides the strength necessary for reliable operation, particularly in builds utilizing a carbine-length gas system with a 5.56 NATO caliber. This part is commonly found in a variety of tactical and sport shooting configurations, making it a staple for builders looking to enhance their AR-15 performance.
Specifications
Ergo Castle Nut for AR-15 - Secure Your AR Build with Precision in Black - 4971-(B)
Available Merchants(4)
Prices checked
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Build history on GunPartPicker
Builders on GunPartPicker first added the Ergo Castle Nut for AR-15 - Secure Your AR Build with Precision in Black - 4971-(B) to a build in February 2026.
Availability is good: it was in stock at one retailer or another nearly every day in August 2026, and today 3 of the 4 retailers we track have it in stock. Prices barely moved in August 2026, holding around $6, so there haven't been real sales lately. Buying today, the lowest price is $6 at BattleHawk Armory, which matches the best price we saw in August.
Updated · from real builds on GunPartPicker · Prices checked · refreshed daily across 35 retailers
Builds Featuring This Part
See all 4 →Builds in the community that include the Ergo Castle Nut for AR-15 - Secure Your AR Build with Precision in Black - 4971-(B)
| Build | Parts | Total |
|---|---|---|
 | 24 | $949.70 |
 | 22 | $2349.09 |
 | 25 | $905.23 |
 | 25 | $1371.84 |
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