Stuck Castle Nut on My AR-15

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Ben86

Ben86

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I have a Bushmaster AR carbine and I really want to put a single point sling attachment on it. I have a Tapco multi-tool to get the castle nut off, but it will not budge. I've tried dousing it with break-free before trying to move it without so much as 1mm of movement. I've put so much pressure when trying to turn it that I've damaged the thread on the buffer tube a little bit.

Is there something missing? Any suggestions would be much appreciated.
 
Is it staked? My Colt castlenut was hell to get off and i had to use a cheater bar. Some companies, such as DPMS, use locktite. Either way i would hit it real good with a heat gun and then try to take it off. If that won't work get a long pipe to use as a cheater bar.
 
Yeah, Bushmaster, Rock River, DPMS, etc., tighten the heck out of those nuts. Heat and perhaps a cheater bar are the way to go. On a few rifles, I've had to destroy the nut to get it off.
 
A good practice is to wrap a couple of layers of painters tape around the buffer tube so that if you slip off the finish won't get dinged. Of course if you go crazy with the heat gun it will start smoking.
 
probably staked or loctited (or both) look closely for a dimple or stamped depression. Maybe use a dremel on the nut to relieve tension. Heat will loosen loctite. The nut is cheap so if you feel like something is going to break, let it be the nut only that needs replacing.
Your nut could be steel or aluminum so use a magnet to determine
 
Yep. They can be a PITA.
I've actually cut them off before, rather than risking damamge to the tube I just replaced the $5 nut.
 
I put my lower in the freezer over night and, and the castle nut popped right off with very little pressure on the wrench.
 
I put my lower in the freezer over night and, and the castle nut popped right off with very little pressure on the wrench.
Click to expand...

Thats not a bad idea. Spraying a coolant through the buffer tube may work better and faster.
 
I put my lower in the freezer over night and, and the castle nut popped right off with very little pressure on the wrench.
Click to expand...

Thats not a bad idea. Spraying a coolant through the buffer tube may work better and faster.
Click to expand...

I'm going to have to try that. The cold should make the metal contract, giving the nut more room to move. If that doesn't work I'll try the heat in case it's loctite. I also need to look more closely in case it's staked. I didn't even know they do that, that's pretty messed up.

This Bushy has notoriously had parts that are supposed to be interchangeable but are a real bear to get off.

I ought to try calling them and finding out what they do to these things to keep them from moving.

Great ideas guys thanks.
 
Ben86 said:
I'm going to have to try that. The cold should make the metal contract, giving the nut more room to move. If that doesn't work I'll try the heat in case it's loctite. I also need to look more closely in case it's staked. I didn't even know they do that, that's pretty messed up.

This Bushy has notoriously had parts that are supposed to be interchangeable but are a real bear to get off.

I ought to try calling them and finding out what they do to these things to keep them from moving.

Great ideas guys thanks.
Click to expand...
Bushmaster did not stake the castle nut or use loc-tite. If you have this it's from a previous owner. Staking the castle nut is usgi spec.
 
You do realize you can break the lower by putting too much leverage on the castlenut wrench if you're using a magwell insert to hold it??????????
 
I'll say again, I highly recommend the correct tool(s) for the job. You need to secure it in a lower receiver vise block if it's that hard to get off.
 
Staking the castle nut shouldn't make it that difficult to remove. That is the proper way to ensure the nut doesn't back out and cause other types of grief (launching springs and detents...) Lock tite is a whole different story.
 
Well in 2008 BM was using some kind of gunk on the threads. I helped a friend get the castle nut off his new BM and it was a bear. Not blue Loctite like RRA but still made for a rough time. That was when I said to myself I'd buy something better.
 
There is a product out there which basically clamps on the buffer tube to provide a single point sling attachment however you lose the ability to move the stock all the way down. Unless you shoot with body armor thats not really a big deal.

I believe there is also a replacement pistol grip with single point sling attachment.
 
Last edited:
Not an expert but you might try to get an impact effect going on, put the wrench on then try to break it free with a lot of force for a short period imagine your hitting it with s hammer
 
I'd just get a new lower and build it to the new specifications. It's very common to stake the castle nut when building an AR, and that's what it sounds like you've got. Or, someone used red loctite. If that's the case, then good luck.

I take it that this is a collapsible length tube? If so, then it's almost certainly staked.
 
The freezer sounds like a great idea. I removed my S&W today and it was staked. It was a pain but I got it off. I love the Magpul CTR! Way better than the previous stock.
 
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