So, one of my rifles, a Noveske NST has a Surefire brake on it.  It's set with Rocksett.

I'm wanting to remove the Troy hand guard and install a Noveske NSR hand guard.  It just chews my hand up, and I don't really like the rubber "octopus" ring inserts.  Doing so will require me to remove the Vltor gas block from the barrel (to get the barrel nut off), which means the brake has to come off too.

As to not damage either the barrel or the brake, any tips to suggest?  I understand a bit of heat may be required.  I do have a heat gun.  Just don't want to booger up my rifle, it's one of my favorites.

ETA:  It has a SS barrel, and I'm moderately concerned about galling of the threads on the barrel.  The instructions to install the brake were followed to the letter, meaning lots of acetone to the threads, followed by an application of Rocksett.

Just put a wrench on it.
Rocksett isn't magic, it's not as tough as red Locktite. Heat shouldn't do anything really, that's the point of Rocksett, it's heat resistant up to 2000 degrees or something like that.
Worst case scenario, you'll need a breaker bar (or cheater bar).
Some people soak in water, which will work, but out of all the flash hiders and silencer mounts I've removed, a wrench has been enough.

When you put it back together, clean the threads of the barrel and mount with a brush (get off all the old rocksett residue) and acetone or other good degreaser and put a drop of rocksett on the threads and put the mount on as directed.

ETA: all that said, if an 800lbs gorilla torqued it on, you'll have trouble regardless of the rocksett.

Many years ago I encountered a Rocksett installed Surefire brake that could not be removed with any amount of force including clamping the barrel in a barrel vise and using a very large pipe wrench on the brake. And applying heat had no effect either.

I contacted Surefire and they advised putting the muzzle end of the barrel in an ultrasonic cleaner with plane water to free the Rocksett.

After a couple of hours in the ultrasonic cleaner the brake removed with little effort.

I put my break in hot water and left it there for a few hours.  It's still a pain but it will come off

Take a brass hammer and hit  the end of the muzzle brake.

It brakes up the Rocksett then apply some force with a wrench and it will come off.

I heard all kinds of advice for rocksett.

Heat does nothing.  Soak it in water.  Boil it in water.  Soak it in kroil.  Put it in an ultrasonic to get water in there and break the ceramic.  Tap it with a brass hammer to break the ceramic.  Etc..etc..

Here is what I found when removing muzzle devices with properly applied rocksett:  None of the above advise will hurt anything, however I do not believe any of it will help anything.  Rocksett is a ceramic, it fills every bit of gap between the threaded barrel and muzzle device.  Nothing gets in there.

What is MOST important is how you will hold the barrel, so that when you apply force, you will not damage anything.  If you vise on the upper receiver, you risk significant damage to the barrel indexing pin, upper receiver, or both.  

You should clamp on the barrel using barrel vice blocks (and risk spinning it and gouging the barrel a bit) or use a Geissele reaction rod.  I really like the reaction rod for adding and removing muzzle devices.  The only downside to the reaction rod, is that it uses the torque set on the barrel extension.  This is generally around 125lbs.  If you try and remove a muzzle device, and that requires more than 125lbs, you risk breaking this loose.  The other downside is any muzzle device that requires that much torque, might risk rounding off on the flats.  Another huge benefit of the reaction rod, is that it does not require removing of the handguard, or removing the barrel from the receiver.

I recently removed an AAC 3-prong hider 51T, and they make a special tool to remove and install these which allows for this torque to be applied without damage, because their flats are small and REALLY flimsy.  That said, what I do is put the barrel on the reaction rod, and set my torque wrench to monitor the amount of force needed to break it loose.  It took right at 85lbs to break the muzzle device free.  Then it unscrewed quite easily.  I would not be too concerned with galling.... just don't apply heat and go slow.