Lots of times the rusting you see in the bore isn't as bad as you would at first think. First make a safety check with the ramrod to make sure there is not a charge in the gun (if you aren't familiar with this procedure have somebody show you how). After this you can soak the bore with a good penetrating oil WD-40 works fine you want to loosen up the rust a bit before the next step. After this you can try steel wool on a cleaning 45 caliber cleaning jag. Keep scrubbing and adding fresh steel wool and oil until you think the rust is gone, then work at it some more. Clean out the bore periodically with a cotton patch and more oil and check the progress with a bore light. When you can no longer see significant residue on a clean patch you can stop. Certainly there will be some pitting, but if your lucky you may still get hunting accuracy out of the barrel. Of course, the worse the pitting is the harder it will be to clean the gun in the future. Another alternative is to buy one of the fast twist replacement barrels that are made for the TC's. These can be had for about $120 and will allow you to shoot conicals with excellent accuracy, if you are into the conical game.
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"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."-Second Amendment to the Constitution