I didn't know they made this beauty. Darn, now I'll be adding this to my list of must have Rugers.Here is what you are talking about. Model 5247. 357/38 with a 9mm cylinder to fit it also.
I believe Magnum on forum here has one. Perhaps he could chime in about it.
Some like the variety of ammo and caliber in the same gun. Make it more fun. Also the ammo for 9mm is much less expensive, $5 to $7 less than .38 & .357I just don't understand why anybody would want to shoot 9mm out of a revolver that isn't dedicated to the caliber? If I wanted to absolutely shoot 9mm because that's all the ammo that was available I would use a semi-auto.
Try the .38 special you will like it, especially out of an overbuilt .357 mag.