Castle nut question

[MarkB1]

Do all AR15 castle nuts have the same width of about 3/8"? I need a shorter castle nut; about 5/16" or 1/4". I have an old Knight's QD sling receiver plate on my AR. It has the old style nut with the holes along the middle of the side of the nut and does not have the castellated cuts of the newer nuts. If I put the castellated nut on the buffer tube the adjustable stock will not catch the last position closest to the receiver. That is why I could use the shorter nut. I could just shorten the stock face that hits the nut, but I would rather not do that.

Does anyone know if such a nut is made?

[markm]

Never heard of any other width on a castle nut. How much shorter does it need to be?

[MarkB1]

Never heard of any other width on a castle nut. How much shorter does it need to be?

About 1/16" to 1/8" would do it.

[ouchonyee]

I've seen a post about the same problem, the thread recommended a bushmaster nut 5310-917-1153, which at the time (2010) was not castellated.
Here it is...

https://www.ar15.com/archive/topic.h...f=123&t=475605

[BCmJUnKie]

My M4 had the problem, it wouldn't lock all the way up, which I never ran in that position anyways.

Check the receiver extension and buff. Retainer. See if you have any room to back it off a turn without shooting the spring out.

It may be enough to get the stock to lock closed. I think this is what fixed mine

[steyrman13]

why not put the castle nut to a belt sander or grinding wheel to reduce the width?

[Hamms]

If you try the grind the side of the nut facing the endplate you will likely end up with an uneven edge that is not truely perpendicular to the RE, so when you crank it down it will try to force the RE offcenter.

[Iraqgunz]

Seems to me that the smarter course of action is to get a different sling attachment if it's going to require crazy mods. Unless I am missing something.

[MarkB1]

I would not want to try grinding the nut. The best suggestion was to try backing the buffer tube out one turn nut I'm not sure I can get the non-castellated nut loose.

The Knight's QD adapter runs about $85 to $90 new. Mine was installed in 2005 and has not given me any problems. It's tight and I may have a problem removing it. I'm not sure the Tapco wrench I have is sturdy enough to remove the nut without breaking. I was just thinking about putting the castellated nut in place of the non-castellated nut that comes with the adapter so I could stake the nut to the adapter. It's beginning to look like I'll just leave it alone as it may just be too much trouble to replace something I'm not having any problem with.

I thought that an easy fix would be to just replace the nut with a castellated nut but the difference in size made for more problems.

[albatrossarmament]

You could always file a small notch into your existing nut to allow for proper staking