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.

Shopping Cart
Strike Industries SI-AR-15/M16 Receiver Extension Castle Nut
Currently Unavailable View Product
Compare (0)
Most Helpful Positive Review better than some
I have several of these. This is just for stocking at this time. I mean it is a castle nut , not much can go wrong. However the threads and wrench slots are better than some. The color is even and match's my upper/lower.
Show
Sort by
Filter by

Castle nut

by Virginian, Verified Owner from VA, United States Written on December 19, 2023
This is a milspec castle nut that has a durable coating and has remained tight since installation
Would recommend: Yes
Was it helpful to you? Yes | No

Good quality

by Gsdduke, from CO, United States Written on December 4, 2018
Castle nut fits nice and snug. Coding looks nice. Metal looks nice and sturdy. Overall very good quality. It fits on my mail spec tube. Strike Industries quality is top-notch. I would recommend this product.
Would recommend: Yes
Was it helpful to you? Yes | No

color is off.

by Mars, Verified Owner from FL, United States Written on June 30, 2018
It’s a dark grey color. Doesn’t match any buffer tube I have, including some from SI. Otherwise it’s a castle nut. Works, but if you expect a rich black color, look somewhere else. Threads are ok. Machining looks fine.
Pros:
  • works
Cons:
  • color
Would recommend: No
Was it helpful to you? Yes | No
There are no reviews that match your criteria. Would you like to review this product?
Last updated 2025-11-12 UTC.