Need help changing buffer tube on an AR....

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Rubber_Duck

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Hi everyone!

I'm replacing the M4-style stock on my Bushmaster with a CAR-style 4-position simply because I like the look and smaller form of the CAR stock, although I understand the improvements of the newer style one. My Bushy also has the A1/C7 upper as well and I think it goes better with the CAR stock. Kinda XM177-ish.

Anyways,
I ordered the CAR stock and when I put it on, the buffer tube sticks out with the stock fully collapsed. I expected this, so I ordered a stock wrench along with the stock. I would imagine this stciking out is because the newer collapsing stocks have the same length of pull as the A2 stock in fully extended (A1 vs A2 LOP?).

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That being the case, I would need to replace the OEM buffer tube with the one that was included with the CAR stock. I know about being careful with the buffer retaining pin and spring as well as the rear pushpin detent and spring (no need to tell me about it), but otherwise it's a simple operation.

While trying to unscrew the castle nut (which is NOT staked by the way), the stock wrench broke! The little nub of metal that goes into the notch on the castle nut just snapped right off. See pic.

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What kind of force is required to remove the castle nut? It seems to be on there pretty tight, and I was putting a lot of force into the wrench before it broke. Now in all honesty I probably got what I paid for, since it was a $5 wrench, however I didn't think it would be a problem as I was only going to use it this one time and saw no need to purchase a fancy armorers wrench. But I need another wrench so what kind do you guys recommend for my one-time use?

Thanks in advance for any help.
 

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So why use loc-tite or stake the castle nut? Any advantage?

I'm assuming the normal way to install the castle nut is to tighten to spec and leave it at that. What does the US Government TM say about installing the castle nut for a carbine?


Thanks.
 
Unfortunately, your problem is, indeed,
Loctite and the dreaded RED one at that!

I went thru that bit of drama a coupla years
back with the castle nut on my RRA lower.

Got to the point where I called Rock River for a fix...

"Well", customer service said, "go to your Home Depot,
pick up a propane torch for hobbyists, and light up that sucker
"!

Get a small hobbyist gas torch, heat up points at
12 o'clock, 3, 6 and 9 o'clock for 30-45 seconds MAX.

Do not allow the finish to get red hot!
A little white discoloration will occur but rubs right off.

You may want to call Bushie to confirm the Loctite,
however, I was told that most companies use it.

Oh, about the wrench -
Once you heat up 2 to 3 points around the nut,
you probably could use a sliplock wrench but
I'd get another castle nut wrench anyways.

Good Luck!

docgary
 
Ok, so I ordered a new stock wrench, one that grabs the castle nut in 3 places instead of just one, so hopefully it won't break this time.

I called Bushmaster and they told me that they actually DON'T use loc-tite on the castle nut, and they said it may help to put the lower in the freezer for a half-hour to help break loose the nut. Never heard of this before but I suppose it couldn't hurt to give it a try. I also have a propane torch (the kind plumbers use to solder pipes) and I would use it as my last resort to avoid damaging/weakening the lower.

But for now I will have to wait until my new wrench arrives before I can try this again.

Thanks again.
 
I did this recently with my Sig 556. Rifle vise (regular vise and my wife's best hand towel), and the wrench you have shown... um, and a hammer... as the Sig peens their keepers.... Ruined the towel and the wrench, but I got the MFSOB off.
 
It is probably red loctite. Instead of heat I use cold. Put the lower assembly in the freezer. Put it in your deep freeze if you have one. Leave it for 3+ hours. Take it out and put it on your bench. Put a brass punch in the notch facing the direction it needs to go to unscrew the castle nut. Hit it fairly hard with a hammer. It should break loose with 2 or 3 good whacks. I've done several with this method. When I've got it off I use a hair dryer to warm up and dry out the inside of the receiver because moisture will condense in there.

ETA that this works becuase cold makes red loctite brittle.
 
What does the US Government TM say about installing the castle nut for a carbine?
My brother is an MP and he wanted to put a different receiver end plate with loops on. When he looked at his rifle he noticed the castle nut was staked on and was obviously meant to stay on permanently. So I gave him my GG&G removable sling attachment that clamps on the buffer tube. I don't know if they are required to be staked but his was.
 
I had the same broken wrench problem when I replaced the stock on my M-4 Bushmaster. I ended up just using a pipe wrench to break it loose.
 
Hi everyone!

My stock wrench came in today and I was finally able to install the shorter buffer tube. Here's how it turned out (sorry about the bad pic quality, took these with cell phone camera):

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Notice the buffer tube doesn't stick out anymore.

The trick was to put the lower in the freezer. With some elbow grease and a few bad words, the castle nut broke loose. Everything went together smoothly and without a hitch.



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You know, when I first brought her home, I was kicking myself for not getting the flat-top upper, but after making a few small changes (sights, trigger guard, hand guards, etc.), I've discovered that this is EXACTLY what I wanted. Kinda IDF-ish/KISS (keep it simple, stupid) carbine. I can always buy the A4 upper later. Or another rifle altogether :)

Thanks for the help guys!
 

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Rubber Duck, thanks for the update. I'm having the exact same problem. I've broken TWO wrenches. I'll try the freezer trick and if that doesn't work, I'll go the heat route. I've got an RRA lower, so it's been pretty much confirmed they use red loctite.
 
Another good idea is to just buy a nice Armorer's Wrench from any of the AR companies (DPMS makes a nice one).

These usually combine a USGI barrel nut wrench, a float tube wrench, and a telestock wrench all into one nice tool for $40 that is better at all three jobs than any of the GI tools. If you plan on doing much building, it is definitely worth the money.
 
I put a couple drops of blue lock-tite on my castle nut when changing stocks cause I don't want it coming loose. I little heat from a propane touch and it comes right off.

And as someone said, if the rifle is going to be used as a weapon, than it should be staked on.
 
I'll go out on a limb here - I think, from my experience, that the loc-tite and staking is overkill. The average AR user should probably worry about a properly staked gas key, not a properly staked castle nut.

Even if it did come loose, it doesn't seem like it'd bring down the gun. You're still pressing the stock into your shoulder - I don't see how something like that could cause a malfunction.
 
Yep...waaaaay out on a limb.

Odds are that when it came loose you would be in the fight of your life saying "Dammit...why didn't I stake that like its supposed to be!!!

It will cause a malfunction when the buffer tube falls to the ground...and its not quick fix either...springs and weights go flying everywhere.
 
Mulliga
Location: Gainesville, Florida

I'll go out on a limb here - I think, from my experience, that the loc-tite and staking is overkill. The average AR user should probably worry about a properly staked gas key, not a properly staked castle nut


Ridgerunner665
Location: Upper East Tennessee

Yep...waaaaay out on a limb.
Odds are that when it came loose you would be in the fight of your life saying "Dammit...why didn't I stake that like its supposed to be!!!

______________________________________

Sorry...I gotta go with Mulliga.

I shoot strictly for sport - and use the AR for target only.
If the castle nut gets loose, the worse case scenario is
the early stages of the stock turning on the lower.

BFD!

Im not in Iraq with zombies zapping me...
and I'm not in a firefight with the local MS 13 boys.

As stated by Mulliga, there are more important areas to be concerned about.

Just my 02 cents!

docgary
 
I've removed two buffer tubes on Bushmasters... one was not an issue, and the other one was exactly like yours... but no Loctite was found on the threads once we gorilla'ed it off.
 
posted by Ridgerunner665

Yep...waaaaay out on a limb.

Odds are that when it came loose you would be in the fight of your life saying "Dammit...why didn't I stake that like its supposed to be!!!

It will cause a malfunction when the buffer tube falls to the ground...and its not quick fix either...springs and weights go flying everywhere.

I don't doubt that can happen. Anyone have any idea the average round count before it does?

I put on a carbine stock using a little CAR wrench like is shown in the first picture. I didn't use any loctite and I didn't stake it. 2k rounds later it is still tight. No full auto, but two defensive carbine classes so there was plenty of hard use.
 
Hi everyone!

I went to the range today, and put 2400 rounds of Federal/Lake City 5.56mm (XM193) through my rifle and didn't have any problems, and after getting home and checking the castle nut, I found that it is as tight as the day I tightened it down. This is good news of course, so I'm not going to worry about anything coming loose.

So I my guess is loc-tite IS NOT needed! Just a good hand-tightening, then a couple of taps on the wrench with a small hammer. This will make it easier to remove the buffer tube in the future if needed. If you're taking your AR to Afghanistan, then by all means stake the castle nut. ;)


EDIT: I put one too many zeros, I meant 240 rounds, NOT 2400. If only I could! Not with current prices for 5.56mm.... :(
 
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