On my hand lapped barrels I will run a patch through them to make sure all the fines from clambering them are out and then coat them. In a factory or potentially rougher barrel I would probably shoot them first to see if they foul much at all. Both shotguns and muzzle loaders benefit from DBC from what I have read. Reduced carbon and plastic or at least easier to clean out.

"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli