+1-800-504-5897 Help Center Check Order Status
About Us Policies Reviews How To
Free Shipping & Free Returns*

FREE SHIPPING on Over 250,000 Products

Shop now and get Free Value Shipping on most orders over $49 to the contiguous 48 states, DC, and to all U.S. Military APO/FPO/DPO addresses.

Enjoy our FREE RETURNS

We want to ensure that making a return is as easy and hassle-free as possible! If for any reason you are not satisfied with your purchase, simply return the item within 30 days of receipt, and we'll cover the cost of return shipping. Learn more about our Return Policy.

  • Entire Store
  • ...
  • Apparel & Footwear
  • Astronomy
  • Everything Else
  • Eyewear
  • Hunting Gear
  • Lab Equipment
  • Military Gear
  • Outdoor Gear
  • Photography Equipment
  • Police, EMS & Fire
  • Shooting
  • Sport Optics
  • Sports & Hobbies
TIP
Shopping Cart

Strike Industries Ultralight Multi-Function End Plate w/ Anti-Rotation Castle Nut Up to 29% Off Plus Blazin' Deal — 2 models

00:59
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
Strike Industries Ultralight Multi-Function Red End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-RED
Strike Industries Ultralight Multi-Function End Plate w/ Anti-Rotation Castle Nut, FDE, One Size, SI-AR-UL-MFEP&ACN-FDE
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
Strike Industries Ultralight Multi-Function Red End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-RED
Strike Industries Ultralight Multi-Function Red End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-RED
Strike Industries Ultralight Multi-Function End Plate w/ Anti-Rotation Castle Nut, Red, One Size, SI-AR-UL-MFEP&ACN-RED
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
1 of 1 videos
Strike Industries Ultralight Multi-Function End Plate and Anti-Rotation Castle Nut
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
1 of 12 images
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
Strike Industries Ultralight Multi-Function Red End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-RED
2 of 12 images
Strike Industries Ultralight Multi-Function Red End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-RED
Strike Industries Ultralight Multi-Function End Plate w/ Anti-Rotation Castle Nut, FDE, One Size, SI-AR-UL-MFEP&ACN-FDE
3 of 12 images
Strike Industries Ultralight Multi-Function End Plate w/ Anti-Rotation Castle Nut, FDE, One Size, SI-AR-UL-MFEP&ACN-FDE
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
4 of 12 images
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
5 of 12 images
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
6 of 12 images
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
7 of 12 images
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
8 of 12 images
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
Strike Industries Ultralight Multi-Function Red End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-RED
9 of 12 images
Strike Industries Ultralight Multi-Function Red End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-RED
Strike Industries Ultralight Multi-Function Red End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-RED
10 of 12 images
Strike Industries Ultralight Multi-Function Red End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-RED
Strike Industries Ultralight Multi-Function End Plate w/ Anti-Rotation Castle Nut, Red, One Size, SI-AR-UL-MFEP&ACN-RED
11 of 12 images
Strike Industries Ultralight Multi-Function End Plate w/ Anti-Rotation Castle Nut, Red, One Size, SI-AR-UL-MFEP&ACN-RED
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE
12 of 12 images
Strike Industries Ultralight Multi-Function FDE End Plate w/ Anti-Rotation Castle Nut in Black, SI-AR-UL-MFEP&ACN-FDE

Tap Tap to Zoom

Government Export Restriction Government Export Restriction
Questions & Answers
what is the set screw size for the detent and spring? Manufacturer Answer

The Ultralight Multi-Function End Plate and Anti-Rotation Castle Nut uses an M3x0.5 set screw for the detent and spring.

by Strike Industries, Manufacturer, July 1, 2026
Is this castle nut and endplate compatible with Strike Industries Advanced Receiver Extension Buffer Tube Manufacturer Answer

Yes, this is compatible with the Strike Industries Advanced Receiver Extension Buffer Tube

by Strike Industries, Manufacturer, April 20, 2026
View All Q&A You Have a Question? Ask!
Customer Reviews
Most Recent Reviews
Great product- a bit tough assemble by Jason, Verified Owner, July 1, 2026
Great looking product but installing the set screw and locking screw are a pain
Most Recent Reviews
Fitment information would be nice. by Rambo, Verified Owner, July 17, 2025
This and one other part cannot be used. This will not work with a MagPul rifle stock/rifle buffer tube.
0/2 found this helpful
Most Recent Reviews
Easy to install by David Bruno, January 16, 2026
Very well made and easy to install, just do not torque the screw to hard it’s very small and will snap.
Most Recent Reviews
Very simple install by Brandon Noe, Verified Owner, May 13, 2025
I always find the concept of changing my castle nut very intimidating, because i feel like I'd mess it up. But with this version, it was very simple and straight forward. So far ive put my gun through 400 rounds since the replacement, and it hasnt go...
Read More...
Most Recent Reviews
Works for most by GalilDan, January 17, 2024
The product does what it describes. Two negative points for me. One I put it on an SA quick detach stock adapter which wouldn't fit due to the QD point being on both sides. I had to modify it by filing off one side. Not a big deal but a point non the...
Read More...
0/1 found this helpful
Most Recent Reviews
Nice, but...... by Alittlepeeved, Verified Owner, March 20, 2025
I had to file away the edges of the anti-rotation tab to make it fit on a mil spec tube.
Read All 11 Reviews

We've got an AWESOME deal for you!

See more Blazin' Deal items
Blazin' Deal
Prices have been cut drastically on select models of this product as part of a special offer. These prices are so low that there's no double-dipping with coupons or any additional discounts - sorry about that. This offer won't last long, so don't miss out!
In Stock
2 Models Available

Show with deals only:

Blazin' Deal
Color
All
Search

Product Info for Strike Industries Ultralight Multi-Function End Plate w/ Anti-Rotation Castle Nut

The Strike Industries Ultralight Multi-Function End Plate and Anti-Rotation Castle Nut are designed to update and upgrade the often neglected castle nut and endplate system. While the traditional endplate and castle nut works extremely well in retaining your receiver extension, the peening of the castle nut is not conducive to rebuilding or upgrading. With the vast amount of aftermarket support for the AR system today, SI feels that theres a need for a secure system as adaptive as you are. Enter the MFEP and ACN. The SI MFEP and ACN offers a built-in anti-rotation QD socket and sling loops. The MFEP is reversible to orientate sling loops to desired side. The Anti-Rotation Castle Nut (ACN) is specifically designed to work with the Multi-Function End Plate (MFEP). Instead of peening the endplate to secure the castle nut, a set screw fulfills this function to allow for multiple uses as you upgrade or update your build. Also never worry about finding a flying takedown pin detent and spring again as there is an included set screw on the MFEP for ease of installation or removal. Consider the Strike Industries Ultralight Multi-Function End Plate and Black Anti-Rotation Castle Nut for your next build or upgrade for both functionality and form of your AR-15 and/or AR-10.image

WARNING: California`s Proposition 65

Specifications for Strike Industries Ultralight Multi-Function End Plate w/ Anti-Rotation Castle Nut:

Manufacturer: Strike Industries
Fabric/Material: Ultralight 7075-T6 Aluminum
Gun Make: AR Platform
Gun Model: AR-10, AR-15
Weight: 1 oz
Condition: New

Features of Strike Industries Ultralight Multi-Function End Plate w/ Anti-Rotation Castle Nut

  • End plate set screw to retain takedown pin detent and spring for ease of installation or removal
  • Multi-Function End Plate is reversible to orientate sling loops to desired side
  • No peening or staking needed with the Anti-Rotation Castle Nut and Multi-Function End Plate design
  • Anti-rotation QD socket
  • Multiple sling loop attachment points

Package Contents:

  • Strike Industries Ultralight Multi-Function End Plate w/ Anti-Rotation Castle Nut
  • X1 Multifunction End Plate
  • X1 Antirotation Castle Nut
  • X1 Set Screw For Antirotation
  • X1 Set Screw For Detent And Spring
  • X1 Loctite Threadlocker Blue242
  • X1 Warning Card

What firearm models does the manufacturer say Strike Industries Ultralight Multi-Function End Plate w/ Anti-Rotation Castle Nut is compatible with?

The manufacturer says that Strike Industries Ultralight Multi-Function End Plate w/ Anti-Rotation Castle Nut is compatible with AR-15, AR-10

Strike Industries Ultralight Multi-Function End Plate w/ Anti-Rotation Castle Nut Orderable Models

List of Orderable Models

  • Strike Industries Ultralight Multi-Function End Plate w/ Anti-Rotation Castle Nut, FDE, One Size, SI-AR-UL-MFEP&ACN-FDE , MPN: SI-AR-UL-MFEP&ACN-FDE , UPC: 793811764482 , Code: 3Q-CAN-ULMFEP-SI-AR-UL-MFEP-ACN-FDE
  • Strike Industries Ultralight Multi-Function End Plate w/ Anti-Rotation Castle Nut, Red, One Size, SI-AR-UL-MFEP&ACN-RED , MPN: SI-AR-UL-MFEP&ACN-RED , UPC: 793811764499 , Code: 3Q-CAN-ULMFEP-SI-AR-UL-MFEP-ACN-RED
Compare (0)
1 item has been added
Add at least two items to compare
Last updated 2026-08-04 UTC.