John,
If you want to treat the cylinders it should work there as well, but you probably will have to shoot several rounds from each chamber.
UBC makes any sort of clean-up easier. It makes cleaning a muzzleloader easier, for instance, and some muzzleloader manufacturers are apparently installing UBC in their factory barrels. It also makes screw-in shotgun chokes much less likely to pick up plastic shot-cup fouling, and if a little does stick it's much easier to get out.
