Who makes a 9 mm revolver?

Answer 1

Assuming you're referring to the 9mm Parabellum/Luger cartridge (a.k.a., 9x19mm), the only one I'm able to think of offhand is Ruger, who used to make a variant of the Speed Six revolver which used the 9x19 cartridge, employing half moon clips to keep the cartridges in the cylinder (the 9x19 isn't a rimmed cartridge, so the conventional method used for rimmed cartridges wouldn't have been effective).