The M47 Medusa Multi Caliber Revolver is one of the most unique firearms in the world, able to shoot any caliber in the .38, 9mm and .357 family. The manufacturer, Phillips & Rodgers, advertises it is compatible with 25+ different calibers, though if you are able to find obscure calibers, it can easily be more like 100+ calibers.
The M47 Medusa was originally advertised as a survival revolver to make it through the apocalypse, accepting many different calibers that could be scrounged up and looted.
Unfortunately many compromises had to be made in the design to accomplish this.
The M47 Medusa is basically a Smith & Wesson K-Frame with a special cylinder. Since this revolver was built to accept so many different calibers, it wasn’t designed to work well with one specific caliber. This means the firearm suffers from accuracy issues and has a number of fragile parts in the design. Fragile parts are the last thing you would want in a “survival” revolver.
While a very interesting concept and unique component of firearms history, ultimately the concept failed. The revolver is no longer being produced and the company is shut down.
These days the M47 Medusa is more of a cool concept than a practical pistol.