A proper fitting patch will never catch fire. I've shot dry patches - first shot only and not had them catch. The only time I've seen smoldering is when trying patches that don't seal.
If a person can't load a tight fitting combination, they should try using a flameproof barrier such as a wad of something - paper, card, felt or fibre shotgun-type wads, or another patch. Every gun I've test this in using thin patches with fibre wads or cards, has given substandard accuracy - but that accuracy was better than without the sealing wad. The best accuracy is given with a tight, ball/patch combination, properly lubed, of course.