eww
Before you decide to remove that sleeve, check with the guy who put it on - assuming you can find him. You may not like what you find underneath. The action may have been trued up by taking a light cut on a lathe, the bluing was probably removed, and it's possible that the action surface was roughed up to get better traction.
If you're satisfied that all is well underneath, the old hot iron or mama's oven method will probably work. You should be able to get enough heat to soften the glue and then it's simply a matter of getting the sleeve started.
Good Luck
Ray
