Castle Nut Won't Budge - Suggestions? (Update - The Nut Finally Budged)

[medved11 71]

I'm trying to remove the factory buffer tube from a Bushmaster lower and it isn't budging at all. Il

I don't see any evidence of the nut having been staked, so I'm wondering if Bushmaster may have used loctite on the nut.

What's the best way to go about getting this thing off?

The tools that I've got on hand are a can of PB Blaster, a TAPCO AR tool, and my lower block and vise.

Should I let this thing soak overnight with a good shot of oil? Try to heat the nut up with a heat gun? A combination of all of the above?

I'm going to replace the buffer with a mil-spec one, so I suppose that I could take the "easy" way and just cut the nut and replace it, but I'd rather try to get this off the "right" way.

Any help would be greatly appreciated.


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[fatty 241]

I would try a hair dryer (or heat gun) for a few minutes.  

[MidwestPX 172]

We had a PD .308 Bushmaster come in for some work several years ago.  The castle nut required channel locks to remove because someone, presumably Bushmaster, used an adhesive on it.  The castle nut was toast but it finally came off. 

[medved11 71]

I just gave it a good shot of PB Blaster. I'm going to let it sit overnight and try again tomorrow with some heat.

 

Assuming that it's going to take a decent amount of torque to get that nut loose (I may try some padded channel locks if the TAPCO tool won't budge it) what's the best way to protect the lower from getting damaged? At the moment, I've got the lower in a Magpul BEV block (which is snugged up in my bench vise).

 

 

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[DeletePLS 178]

is there a sling adapter on the rifle?  my lwrc has 2 small set screws that hold the nut from coming loose.

[n4p226r 105]

I'm pretty sure bushmaster uses loctite of some sort.  apparently thats cheaper than the 60 seconds it takes to do it correctly.  i'd try some heat personally

[High Exposure 5,664]

Don't worry about using padded channel locks to save the castle nut. The castle nut and the receiver end plate shold be replaced if you are installing a new reveiver extension anyway.

 

As others said, Bushamster cuts corners by using some some kind of Loctite instead of staking (Keep in mind, they take other shortcuts as well - keep an eye on your BCG).

[medved11 71]

There's no sling adapter on this one, just a solid end plate.

 

is there a sling adapter on the rifle? my lwrc has 2 small set screws that hold the nut from coming loose.

 

 

 

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[medved11 71]

Soaking overnight with a couple of shot of PB Blaster didn't loosen anything up, so they (Bushmaster) must have put something on the threads. I'm going to try some channel locks when I get home tonight. I was thinking about using a cheater bar with the TAPCO tool but I'm afraid of warping the receiver. I ordered a stock hardware kit from BCM, so I've got a new castle nut, end plate, and a VLTOR tube ready to go once I can get this other thing off.

 

I'm actually going to replace the original bolt and BCG as part of this project. I figured that I would decrease the odds of any potential headspace issues if I bought the barrel, bolt, and carrier from the same manufacturer.

 

Don't worry about using padded channel locks to save the castle nut. The castle nut and the receiver end plate shold be replaced if you are installing a new reveiver extension anyway.

As others said, Bushamster cuts corners by using some some kind of Loctite instead of staking (Keep in mind, they take other shortcuts as well - keep an eye on your BCG).

[medved11 71]

I'm going to try your channel lock solution tonight since the PB Blaster soak didn't do anything overnight.

 

What did you use to secure the lower? Was it just in a vise?

 

the reason that I'm asking is that I'm concerned that I'm going to end up warping or cracking my lower in the process of trying to remove an $8 nut.

 

We had a PD .308 Bushmaster come in for some work several years ago.  The castle nut required channel locks to remove because someone, presumably Bushmaster, used an adhesive on it.  The castle nut was toast but it finally came off. 

[Vlad G 345]

Apply heat first, before force. A lot of loctite products soften up with heat which will mean you don't need to risk other damage by applying force first.

[medved11 71]

One more (potentially stupid) question before I try this again when I get home tonight...

 

If I'm facing the rifle from the rear, I should be trying to turn the castle nut counter-clockwise, correct?

[High Exposure 5,664]

Yup

[medved11 71]

I got the nut to come loose!

 

I figured that I'd give it one more try before leaving for work. I didn't use any heat, so I guess the penetrating oil just needed another couple of hours to do its thing

 

Here's what I did:

 

1. Took the lower out of the vise and put in on the floor (safety side down) with a pile of garage rags underneath the protect the finish on the lower

2. Held the lower with my support hand and lined up the wrench with the castle nut

3. Leaned on the wrench with my strong hand as hard as I could

4. The nut resisted a little but let go after about 30 seconds (which was nice because it felt like my spleen was about to rupture)

 

I don't see any evidence of loctite on the threads or castle nut. It must have just been torqued on in the factory by the resident gorilla.

 

Thanks for all of the tips and suggestions

[chris327 30]

i had the same issue a few weeks ago removing it on a bushmaster. not staked no evidence of loctite either i just heated it up for a min and it came right off. i really think heat is the best way to remove any screw or bolt that's tight or not coming loose. way better than any pb blaster or anything like it.

[medved11 71]

I was reading a bunch of threads on other sites last night and the castle nut seems to be an issue on Bushmasters, S&W, and Rock River Arms ARs (at least those were the top 3 that I saw mentioned repeatedly).

 

Heating the nut up was going to be my next move if it didn't come off with the extra leverage that I got by putting the receiver on the floor

 

i had the same issue a few weeks ago removing it on a bushmaster. not staked no evidence of loctite either i just heated it up for a min and it came right off. i really think heat is the best way to remove any screw or bolt that's tight or not coming loose. way better than any pb blaster or anything like it.

[Ace08066 2]

I was reading a bunch of threads on other sites last night and the castle nut seems to be an issue on Bushmasters, S&W, and Rock River Arms ARs (at least those were the top 3 that I saw mentioned repeatedly).

 

Heating the nut up was going to be my next move if it didn't come off with the extra leverage that I got by putting the receiver on the floor

 

Man, I had this long, thought-out reply all typed up and said, "Maybe I should just read the recent comments, in case he got it already."  Sure 'nuff, you already got it! lol.

 

Well, biggest point I was going to make was I'm certainly no gunsmith but I was a mechanic for a good part of my life thus far and I can tell ya I've never gotten a nut to come loose with a hair dryer or a heat gun.  Either Acetylene + Oxygen torch or a conduction gun if you're worried about the surroundings.  

 

WD-40 is evil.  PB Blaster is love!

 

Glad ya got it, tho.

[medved11 71]

Thanks - I've never been so happy to get a nut to come loose before. 

 

Man, I had this long, thought-out reply all typed up and said, "Maybe I should just read the recent comments, in case he got it already."  Sure 'nuff, you already got it! lol.

 

Well, biggest point I was going to make was I'm certainly no gunsmith but I was a mechanic for a good part of my life thus far and I can tell ya I've never gotten a nut to come loose with a hair dryer or a heat gun.  Either Acetylene + Oxygen torch or a conduction gun if you're worried about the surroundings.  

 

WD-40 is evil.  PB Blaster is love!

 

Glad ya got it, tho.

[Schrödinger's cat 87]

 

WD-40 is evil. PB Blaster is love!

 

Glad ya got it, tho.

Why is WD-40 evil ? I know it's not a good lubricant and that it gums up and becomes hard when dirt gets in it, but what's wrong with using it to try to get something loose ?

[PK90 3,570]

You should have just thrown it over the wall.

 

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[checko 180]

You should have just thrown it over the wall.

 

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+1 How did I not think if that

 

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[Vlad G 345]

The reason heat tends to work on ARs is because of bimetal construction. The two big things can be torqued, glues, stuck, or loosened are the barrel nut and the castle nut and they are both steel on aluminum, so they heat up an expand at different rates. This doesn't work so good on steel on steel bolts, but for me it has always worked for those two nuts.

 

Yes, some barrel nuts are aluminum, there you hope the big mass of the barrel nut takes the hit first and expands before the receiver.

[Eric. 9]

The reason heat tends to work on ARs is because of bimetal construction. The two big things can be torqued, glues, stuck, or loosened are the barrel nut and the castle nut and they are both steel on aluminum, so they heat up an expand at different rates. This doesn't work so good on steel on steel bolts, but for me it has always worked for those two nuts.

 

Yes, some barrel nuts are aluminum, there you hope the big mass of the barrel nut takes the hit first and expands before the receiver.

While heat is the best method, imo, bi metal construction works *against* you here.  

 

The castle nut is steel.  The receiver ext is aluminum.  If you heat both up at the same time, the aluminum expands faster and more than the steel.  That basically makes the nut tighter.

 

If you're gonna use a torch, use a fine nozzle that you can pinpoint the heat on the castle nut itself and not on the receiver ext threads.

[medved11 71]

I'm not sure if would work or not but, while I was researching ways to loosen my castle nut, I saw (on other forums) a couple of posts that suggested using a soldering iron as a way of applying heat to the castle nut without heating  up the extension. 

[T Bill 649]

i don't think so.  To pointed to get enough heat across nut.  Hair dryer is best.  Nothing there to damage anyway, until you get to about 1100F

[Ace08066 2]

Why is WD-40 evil ? I know it's not a good lubricant and that it gums up and becomes hard when dirt gets in it, but what's wrong with using it to try to get something loose ?

 Well WD-40 is not a penetrating fluid, it's a water displacer.  PB-Blaster does a far better job at penetrating into bolt threads.  My biggest gripe with WD-40 is, even though the maker's vehemently deny the accusation, I've seen with my own two eyes that it actually promotes rust.  After using WD-40 to break a subframe bolt loose many a year ago, I jacked up the car a few weeks later to find that only the areas I had sprayed with WD-40 had a thin layer of rust forming.  Everything else had nothing.  Seen a few similar things since. 

 

Don't get me wrong, it has it's uses...  But you'd never catch me spraying it on my guns.  Just my opinion, tho.

[Eric. 9]

, I've seen with my own two eyes that it actually promotes rust.  After using WD-40 to break a subframe bolt loose many a year ago, I jacked up the car a few weeks later to find that only the areas I had sprayed with WD-40 had a thin layer of rust forming.  Everything else had nothing.  Seen a few similar things since. 

 

 

If I had to guess, it's probably more like WD-40 removed the rust protectant coating from the area of the metal, rather than the actual WD 40 causing rust.

[TonyS. 12]

FWIW, my ff handguard from Midwest Industries included a small vial of adhesive they say you must use on the barrel nut or you void their warranty. Yet all the vids I've seen on installing a ff handguard has the host using grease on the nut.

[Vlad G 345]

While heat is the best method, imo, bi metal construction works *against* you here.  

 

The castle nut is steel.  The receiver ext is aluminum.  If you heat both up at the same time, the aluminum expands faster and more than the steel.  That basically makes the nut tighter.

 

If you're gonna use a torch, use a fine nozzle that you can pinpoint the heat on the castle nut itself and not on the receiver ext threads.

 

Yes, to a point. In my experience it isn't so much that you expand the nut around the bolt, but that you get them to move against each other breaking whatever bond they might have.  The other is the difference in specific heat of metals. If I remember correctly aluminum will expand about 50% more then steel for each degree absorbed, but it takes twice as much energy to get aluminum to gain a degree as it takes for steel, which means that all things being equal the steel part will expand faster, specially if the heat is applied to the steel part. But this stuff is dragged from deep in the back of my hand and I may have my numbers wrong.

 

Of course applying heat just to the nut is best.

[PK90 3,570]

FYI, I have previously used my freezer to break parts loose. It works better than heat sometimes.

 

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