When Ruger first introduced the .357 Magnum Blackhawk Convertible, part of the advertising was that there was practically no place on Earth that ammunition could not be found. The 9mm cylinder of course could handle the 9mm Parabellum round and the 9mm Glisenti cartridges. In the .357 Magnum cylinder .357 Magnum, .38 Special, .38 Long Colt and .38 Short Colt cartridges could be used, as well as .38 Super and .38 ACP, and, in a pinch, .35 WSL could be fired.
One of the first things I did when I got my Blackhawk (not a convertible) was try all the .38 cartridges available at the time. For a real indoor gallery load, try the .38 Short Colt. I fired some of these into some water (it was safe to do so at that location) and I could have made a bigger splash by throwing the cartridge into the water. I don't think these would penetrate a tin can.