Pyrodex "P" is all I use, in both side locks and the ROA. Never a corrosion issue, here or in Michigan. Although, I clean immediately after use. Soapy hot water, followed by couple of rinses, with hot tap water. Gets barrel so hot that it's unable to be held bare handed. I swab the bore with a patched soaked in bore butter.
I have Ballistol and use it on all firearms. I will dilute it to moose milk to swab a muzzleloader if I don't have time to clean, immediately.
I have left my unfired Renegade loaded for more than a year, multiple times, with Pyrodex. Never fails to fire. The ROA, took a buck, early in the season. Cleaned only the barrel and the one fired cylinder, with Ballistol moose milk. Left it that way till the next spring, without issue.