The fire lapping works, but I would give it a dose of Evaporust first. Then put a little lapping compound on a piece of steel plate, put a conical bullet of the proper size on the plate, and with another piece of good flat steel roll the bullet back and forth until the abrasive is inbeded in the bullet. Now, load a good stiff load, and fire the bullet. You will have to repeat this several times, and you should mop the bore between shots. You will feel the bore getting smoother, but don't go too far, a T/C doesn't have very deep rifling to start with.
Hungry Horse