UMC was offering smokeless powder loadings in a wide variety of calibers, including rimfire, centerfire revolver, centerfile rifle, and shotshells in their 1895 ammunition catalog. I have always suspected that many, if not most, of the old S&W top-break revolvers of that era (and handguns from other manufacturers as well) never fired a single black powder cartridge. If you are concerned about the safety of your Model 91 barrel, you could always use CCI CB caps. I don't believe standard velocity .22 target loadings would be unsafe either.