Take a small mouth olive or capper glass jar and add a mixture of Kano Kroil oil and Shooters Choice to a depth deep enough to cover the anterior portion of the choke 1/8" above the threads of the choke tube. Set the barrel down in the mixture and stuff paper around the mouth of the jar to preclude evaporation and let it sit, and let it sit. You can remove the barrel periodically and tap on it w/ a non-marring plastic head hammer and lightly heat with a waving motion w/ a propane torch or heat the hell out of it with a hair dryer on high. The soaking solution can be filtered through a coffee filter and added back to the Shooter's Choice once the tube breaks free. It may take several weeks, but this will usually do the trick. If this doesn't work the usual alternative is to have the tube drilled or lathed out and the barrel threads thoroughly cleaned and rethreaded.
