Gunsmithing How the hell do I get this damn barrel nut off? (ar-15)

Johnny Sasaki

Johnny Sasaki

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Minuteman
Sep 26, 2010
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Lost in the Universe, on a ship, a living ship...
#1
Seriously, this thing is really getting frustrating. I finally got all the parts in the mail that I need to get it off, which was an ordeal in itself (the wrench and the block for the vise), and the thing just won't budge. I've tried heating it up (and melted my friggin' leaf blower tip when the heat gun tipped over), I've tried spraying WD-40 all over it. Nothing. I'm literally hanging on the wrench.

Also, who the hell designed this barrel nut anyway? One of the dumbest designs ever. I'm convinced they couldn't make this this any harder to get off. Not only is it torqued like a motherfucker, but I gotta push in against the spring just to get the wrench to lock up.

It's a colt mk18 upper btw. I can see a giant crack on my bench where my vise is literally about to snap right off the table. With my luck, probably hitting me square in the face in the process.


So how the hell does one remove one of these things? I'm tempted to just take it to a gunsmith, but at this point it's personal, lol.
 
Last edited:
#3
Probably a bad idea but I once read someone in the same situation attached the wrench to the nut via loctite (don't know if he used blue or red), waited a day or two for it to cure and pounded away with a heavy hammer...
 
#4
BusterB said:
Heat makes things expand=tighter. Throw it in freezer several hours and try

Sent from my SCH-I605 using Tapatalk
Click to expand...

Yeah, I just visited ar15.com and one guy said that as well. However, there were also plently of people saying to heat it up too. Probably because it most likely has loc-tite on it. I'll throw it in the freezer for a while and report back. Probably gonna dremmel off the delta ring if that doesn't work, as I don't need that for the new rail.
 
#7
I don't know which wrench you are using, some you can attach a breaker bar to....longer handle= more leverage. Also which ar15 block are you using? Unless you are using something that retains the upper well I would be worried about torquing to much and breaking the upper.

If you are using something that secures the upper remotely well I'd use the breakerbar method, if that's not an option I'd give the wrench a few good wacks with a rubber mallet(human impact wrench)...that should pop the nut loose. Uppers are pretty strong, I had a barrel nut on an ar that some son of a bitch locktited and over torqued that took a little over 100ft lbs to break free and I didn't damage the upper getting it off and I was only using a DPMS panther claw to secure the upper in combination with one of those breakerbar looking automotive torque wrenches.

Good luck.
 
#8
Slitting wheel....no sense in killing yourself. Might bend something you don't want to as well. Make 1-2 cuts in it going until you think you're about thru and stop and bang it with a medium weight hammer a few times.
 
#9
spend $50 at your gunsmith,had to go to one to do the same once,just a nightmare barrel, but have done 5 more without help. Walked in with tail between my legs, after 3 days of pounding heating, ruined 1 set of wood blocks in barrel vise,marred up finish on receiver by action wrench.
 
#10
WildBill3/75 said:
I don't know which wrench you are using, some you can attach a breaker bar to....longer handle= more leverage. Also which ar15 block are you using? Unless you are using something that retains the upper well I would be worried about torquing to much and breaking the upper.

If you are using something that secures the upper remotely well I'd use the breakerbar method, if that's not an option I'd give the wrench a few good wacks with a rubber mallet(human impact wrench)...that should pop the nut loose. Uppers are pretty strong, I had a barrel nut on an ar that some son of a bitch locktited and over torqued that took a little over 100ft lbs to break free and I didn't damage the upper getting it off and I was only using a DPMS panther claw to secure the upper in combination with one of those breakerbar looking automotive torque wrenches.

Good luck.
Click to expand...

I'm using the Wheeler Engineering vise block and the DPMS wrench. I was literally off the ground just hanging on the thing. Vise is about to snap off the bench, lol. It's on there for real. It's been in the freezer for a couple hours, so lets see what happens now. If not, I'll try soaking it with some more wd40, and then if that still doesn't work I'm breaking out the dremmel and shits gonna get real. ;)
 
#12
It's probably glued with loctite, heat the outside of the nut quickly to about 400 f (I prefer to use a propane torch over a heat gun) touch a bar of beeswax (not parafin) to the joint, the beeswax will penetrate the joint and instantly kill the loctite.
 
#17
I had the same thing with a JP. the holes in the aluminum barrel nut gave way and then I was forced to use a large pipe wrench. it finally came off. it was a combination of Loctite and a sleeve over the barrel extension. good luck man.
 
#18
using a slitting wheel on the barrel nut is not that horrible of an idea. make a notch (not all the way thru) and put a screwdriver in it and bang it a few times. Then wrench it off. If it is still stuck flip it over and cut another relief cut opposite side of the first one. Just go slow, its not the end of the world if you do in fact cut into the threads a little bit. If you're bent on DIY, these are the tricks. Trust me I have built/repaired/fixed-stupid enough ARs.
 
#19
0311 Hesco said:
using a slitting wheel on the barrel nut is not that horrible of an idea. make a notch (not all the way thru) and put a screwdriver in it and bang it a few times. Then wrench it off. If it is still stuck flip it over and cut another relief cut opposite side of the first one. Just go slow, its not the end of the world if you do in fact cut into the threads a little bit. If you're bent on DIY, these are the tricks. Trust me I have built/repaired/fixed-stupid enough ARs.
Click to expand...

That's actually exactly what I ended up doing. Worked like a charm.

Finished product:

20131201_035529.jpg
 
#20
Glad it worked. That's been my go-to as well. It took me a long time to nerve-up and get that close to the threads. When I did it was fine, and after that I would go straight to that then on.
 
#21
For future reference, when you have something that stuck, go to your local supermarket fish section and ask to buy a block of dry ice. Cover the barrel nut and receiver in dry ice in a foam cooler. It'll come off. The metal shrinkage at -109F is a heck of a lot more than the shrinkage at 32F. It's also how I fit interference fit bearings to machine shafts...works like a charm.

Ohh yeah, and btw, WD40 is best suited to display not use. Go get some real penetrating oil like Kroil or PB Blaster.

--Wintermute
 
#22
I work in the aviation world and when I have to replace slip fit bushings (say on a landing gear) we use liquid nitrogen to freeze the bushing and we heat the fitting with a propane torch.... bushing just falls right in (cold:shrinks it a couple thousandths/Heat expands it a couple thousandths).

The trick with the dry ice on the barrel and a quick touch with the torch could've been enough... Glad to hear you got it.
 
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