Hmmm. '.38 super' was/is a rimless cartridge developed by Colt for some models of 1911. Supposedly able to punch through all known body-armor in the 1930s.

While it is certainly conceivable that some revolvers were converted to take moon clips of .38 super, I have never heard of such a thing.

Still, if it exists or existed, someone one this bulletin borad should know about it.

Good luck