I got my barrel turned a while back and got a muzzle brake perminantly attached. I went to install a free float rail system and BAM the barrel nut will not move. I have a receiver block, barrel wrench, and breaker bar. I do not have a vice but I fix that normally by holding or putting a knee on a vice block. Today I stacked a book on top of the block stood on it while bushing on the breaker bar. NOTHING. The thing is really tourqed in there. It moved me twice, wripped the receiver out of the block once (completely lifting me that ways over 200lbs) and started bending the notches on the barrel nut. IT is frigging rediculous that he put it on this tight. I normally do not have this problem. My only option I really have left besides taking it to the shop, putting it in the vice, and cranking it with an impact wrench will be to cut the barrel nut. I figure if I cut a couple of notches in the nut and bump the cut with a wedge and mellet it might just break with I turn it and come off.

Any thoughts?

I suggest you find a vise to borrow before you break anything.  You're not going to get much more than 30 or 40 ftlbs of usable torque using your ass to hold it in place and the spec allows for the nut to be put on with as much as 80 ftlbs.  If the upper was assembled without proper grease then it may take a lot more to get it off of there.

Editted to add that if the receiver and barrel needed that much force to out them on in the first place then you may need that much force to isntall the free float tube so you're going to want that vise available.  

Also, you say that a muzzle brake is permanently attached.  How are you getting the gas block on and off?

Haha, funny you should mention that. I plan on doing a do it yourself cut down block. This would allow the barrel nut to come off over top of it. That is why I would not be heart broken if the nut was destroyed. I am just going to trim the gas block and if I screw it off I can cut a small not by the allen wrench hole and pop the arm off that holds it on. Then I can replace is with the two peice yankie hill. Like I said I never had one this tight. I sat a book on the thing and put both feet on it. I dont remember the formula for tourqe but I would think that it would still be more than 50% to lift my entire body through leverage.

I have access to everything in an auto shop so I can get a vice but still done know why it is this damn tight.

There formula for torque is your perpendicular component of force times the torque arm distance.

But that doesn't really demonstrate anything. You're still not getting enough torque, unless you're using a vise. The fact that you were able to do it in the past demonstrates only that the barrel was improperly torqued. Don't get the power tools yet.

I had trouble recently with an AR10 barrel nut. After shearing off a couple of teeth on the nut I decided to try the old freezer trick. I sprayed it down with some liquid wrench and put it in the freezer for about four hours. She loosened right up.  Good luck.

Ok that thing is about to go in the freezer.

The block is designed to be put in a vise.  You aren't gonna get much torque doing it any other way. You got a receiver vise, you're halfway to doing the job right so why stop there? I'd say quit screwing around and get or borrow a vise. You'll be amazed at how much easier the job is with one.

Oh yeah I forgot. After I took it out of the freezer I put it in a vise.

Quoted: Oh yeah I forgot. After I took it out of the freezer I put it in a vise.

Tried it again last night after it got out of the freezer. I think I am going to stop by somewhere where I can use a vice tomorrow. I dont know because the thing looks like it is pretty much destroying the barrel nut now. I think I might have to dremal it off anyway. I know that regardless I am going to have to cut the thing because it will not fit over a low profile gas block either. We will see.

I might just walk up into the wood shot I walk past at the university campus tonight. Just stroll on in to the room and go "Hi, can I use your vice?" haha.

You can get a vice from Harbor freight for $30.  Why risk screwing up a $90 part for $30?

Heck you can get one from Lowes for $20. Sure it's not top of the line but mounted to a 3/4" piece of plywood or a 2x6 it would probably work fine.

Check out this thread for more info on a vise for apartment dwellers.

That is a good thread. I think I might buy a vice but right now I dont need to. My father owns an auto repair shop not to far from here. I do have all my compressor and air brush stuff here, I still go there to beed blast my stuff. I can go in there and use a vice if I want but it just isnt indicative of a sunday afternoon project. I will go in there tomorrow and use it.

I just thought it would be funny as hell to show up to campus an hour or so early for my classes and stop by the wood working dept with an ar15 upper and just roll in and use a vice and walk out. Hell everyone just walks in and uses the computers in all the rooms and buildings anytime they feel like it. The look on everyones face would be priceless.

Quoted: I just thought it would be funny as hell to show up to campus an hour or so early for my classes and stop by the wood working dept with an ar15 upper and just roll in and use a vice and walk out. ...The look on everyones face would be priceless.

Just tell them it's an art project representing the oppressiveness of a liberal crazed society, which forces men to fight a war with only half a rifle.  

Yeh I wish I had brought it, on the way to class I was acosted by a guy who wanted me to sign a petetion to ban the second amendment rights. I was like "why would I sign a thing like that" he said something like to keep myself safe and to prevent random people from walking around with guns. At that point I so wanted to pull up my shirt exposing my sig and say "that is what this is for" but I didnt I just said "yeh that petition isnt going to work."

Going to take the upper in a few min to get done. I shouldnt have a problem with the amount of equipment they have there. Only problem is that I have to go back up there after I cut down the block to put on the other peice.

What type of barrel nut wrench are you using?  The old, three prong GI unit is a POS.  Use something like the DPMS multi-wrench.  It has much more contact area and I have yet to destroy a barrel nut, much less damage one, and I've run into some tight ones, including an AR-10 barrrel nut, which came off just fine.

Took it in and used the vice. I put my weight into it and it came off without too much of an issue. My only thing after that was that I couldnt cut my gas block down enough for the new barrel nut to go on. I then had to cut the gas block off of my barrel and I will then pick up a new two piece one today. I tourqed the new nut down to line up the gas tube and done.

Quoted: My only thing after that was that I couldnt cut my gas block down enough for the new barrel nut to go on. I then had to cut the gas block off of my barrel and I will then pick up a new two piece one today. I tourqed the new nut down to line up the gas tube and done.

I just read this topic for the first time tonight.
As I was reading through the posts, I was going to mention that the cut down front sight base is not going to be low enough to get the barrel nut or handguard over, but it looks like I was too late.
I assume you found the YHM clamp-on gas blocks by now...

Randall

Yep, they look real nice so I ordered one. I was going to have to cut something. Either the front sight or the barrel nut. Since I needed to get the new one on cutting the old one off really wouldnt have helped that much. It was kind of cool being in my dads auto shop and all the mechanics gathering around and watching me mess with this thing on the vice. Soon I noticed some customers had drifted in and started watching right as I popped the old barrel nut off and putting the new one on.