A buddy of mine just bought a Yankee hill free float tube for his Ar (Rock river 9mm) he tried the wrench no go. he took it to a smith , the smith could not get it, he broke the wrench in the process. They said they have tried soaking it in break free, heat and the nut still won't back off. Any suggestions would be great.

Aluminum will shrink as much as 6/1000 of an inch when chilled with dry ice. This translates to 6 on each side of the threads 12 /1000 of an inch. The barrel nut should unscrew given this kind of relief.

Quoted: dremel cut the nut - just put a slice in it, enough to weaken it - torque it with the wrench, should break & break free BTW - Righty Tighty, Lefty Loosey

+1

freeze it. That will usually get it.

Quoted: freeze it. That will usually get it.

That's what I've heard, overnight in the freezer.

dremel cut the nut - just put a slice in it, enough to weaken it - torque it with the wrench, should break & break free




BTW - Righty Tighty, Lefty Loosey  

No personal experience, but I've heard that dry ice works. The idea is to shrink the inside part (barrel) by chilling it, while simultaneously expanding the outside part (nut) by heating it.

Try the cold first.  Dry ice is fine, 7075 aluminum actually gets stronger at cryogenic temps.  You need to trim off the bum lugs on the barrel nut.

Use an upper action block and a full lug wrench, not the cheesy 3-pin types.  Pin types are fine for assembly only.  

If this doesn't work, degrease the barrel nut with brake cleaner.  Apply Sweet's 7.62 bore cleaner and let soak overnight.  The problem is aluminum oxide, probably from getting the rifle wet.  ?Aquabumping?  HA!  Anyhow, the ammonia in Sweet's may help dissolve this oxide.  It can also damage anodization so watch out.

If Sweet's won't work, degrease again with the brake cleaner and then hit it with a few drops of commercial ammonia.

What happens when steel is in contact with aluminum is an electrochemical reaction.  The steel rusts until it makes contact with the aluminum.  The next time it gets wet, the rust is then reduced by the aluminum, making thick, aluminum oxide and a black, smutty mud of iron.  The corrosion continues every time it gets wet.  Now the aluminum oxide turns into a concrete-like mass, expanding every time it gets wet and siezing the barrel nut.

Now wait a minute.

You're asking a question actually related to an AR-15??

On this board!!!?????

Quoted: Aluminum will shrink as much as 6/1000 of an inch when chilled with dry ice. This translates to 6 on each side of the threads 12 /1000 of an inch. The barrel nut should unscrew given this kind of relief.

Nope.  That's .006" per 1.000".  That means you have to have a 1" thick piece of aluminum to shrink .006".  

But thanks for bringing back a two month old topic!

Thanks a bunch guys. Keep em coming. I'll update you later.

Remove the gas tube first!

From what I've read, the freezing method works pretty good.

Unless you already have one, I'd recommend the type of upper reciver block that has the insert that replaces  the bolt carrier to clamp it down with.

If it's still a no-go you might try a pipe wrench... the longer handle will give you the extra leverage.

We drimmeled it off. It worked out fine.Thanks again.

When your smith assembles it make sure he uses the proper Moly-Disulfide great (w/o graphite).  I'll bet whoever put on that barrel nut didn't grease it properly.

Quoted: We drimmeled it off. It worked out fine.Thanks again.

No THANK YOU???  

I’ve used the “freeze over night/pipe wrench” method.......it works.

Bushmaster recommends the freezer trick, the military FM recommends the pipe wrench.


My barrel nut troubles.

I have found the best method is to box it up and send it to ADCO.  The rough handling by the Postal Service will guarantee that when they open the box, the barrel nut will have jarred loose enough that it comes right off.  

I've got a pretty large breaker bar for this type of scenario. I don't have the patience for freezing, so I usually apply a liberal amount of penetrating oil, let it sit for a few minutes, and then go to town.

So far I've been pretty lucky-I haven't broken an upper yet. When I freefloated my 6721 I broke a wrench though

No prob, I was asking for a what happened from this scenario.