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Strike Industries
Overview
The Strike Industries End Plate and Anti-Rotate Castle Nut is a standard steel component designed to secure the buffer tube to the receiver while preventing any rotational movement. This combination provides a reliable foundation for your AR-15 build, ensuring that the buffer tube remains aligned during operation. You will often find this end plate and castle nut set used in mid-length gas system builds chambered in 5.56 NATO, where durability and stability are essential.
Strike Industries End Plate and Anti-Rotate Castle Nut for Receivers, Red - SI-AR-UL-MFEP&ACN-RED
Strike Industries End Plate and Anti-Rotate Castle Nut for Receivers, Red - SI-AR-UL-MFEP&ACN-RED was the third most added end plate on GunPartPicker in August 2026, behind the BRAVO COMPANY AR15/M16 QD Receiver End Plate (BCM-EPM4-QD), with about 17% of all end plates added to builds. Down from #2 in May, June and July. Builds with this end plate are split between 5.56 NATO (50%) and 300 Blackout (17%), split between mid-length (50%) and pistol-length (30%) gas systems, and mostly AR-15 (78%, then AR-10 22%).
Availability is good: it was in stock at one retailer or another nearly every day in August 2026, and today 5 of the 6 retailers we track have it in stock. Prices barely moved in August 2026, holding around $35.95, so there haven't been real sales lately. Buying today, the lowest price is $35.95 at Palmetto State Armory, which matches the best price we saw in August.
Updated · from real builds on GunPartPicker · Prices checked · refreshed daily across 31 retailers
We ranked every end plate by how often it shows up in real builds on GunPartPicker.
Read the guide: AR-15 End Plate Guide →The part most often added in each category by the 505 builds that include this one
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Aggregated and anonymized data showing how builders use this product
Builds in the community that include the Strike Industries End Plate and Anti-Rotate Castle Nut for Receivers, Red - SI-AR-UL-MFEP&ACN-RED
| Build | Parts | Total |
|---|---|---|
 | 23 | $2733.07 |
 | 30 | $5139.04 |
 | 27 | $2159.99 |
 | 28 | $2691.02 |
 | 37 | $6634.63 |
 | 22 | $3053.02 |
 | 19 | $627.90 |
 | 25 | $1858.95 |
| 22 | $2171.27 |
 | 34 | $4836.16 |
 | 24 | $1613.63 |
 | 22 | $1240.53 |
4 global ratings
Top reviews
Secured my buffer tube on my new 5.56 build with absolutely zero issues. This thing is built solid and the anti-rotate feature is a smart addition. Couldn't ask for more from a basic AR component like this.
It's an end plate and castle nut set. Does what it's supposed to do by keeping the buffer tube in place. The steel feels standard, not premium but not flimsy either. The red color adds a bit of pop.
Was looking for a reliable way to keep my buffer tube from spinning during installation and operation. This SI set does the job perfectly. The castle nut staked well and the end plate design prevents any wobble. Great for AR builds.
This Strike Industries end plate and castle nut feels sturdy enough. The red color is a nice touch for my build, though it was slightly darker than I expected from the photos online. Overall, it holds the buffer tube securely.
