I have never had shotgun wads or rifle patching catch fire. It is all in what you lube with.
I would not quite agree with that. Fit of ball and patch is VERY important, maybe the most important aspect. The only time I have seen smoldering patches
is with people using loose ball and patched loads. Gas/flame blow by seems to be the culprit in igniting patches, which stands to reason.
Taylor and I have NEVER had as smoldering patch, from smoothbores or from rifles. That just doesn't happen and we
use a variety of lubes, from spit to WWWF + oil to Neetsfoot oil, Track's Mink oil or Bear grease/oil.
In my .69, using dry paper ctgs. & 165gr. never a smoldering 'ctg., either - just confetti form that gun, and solid ctgs. from the Brown Bess with 85gr. 3F.