Can anyone tell you if there is such a shotgun like a rolling block 24 gauge?

I'm sure there probably is, but I can't locate one in any of my references. If you have an idea who might have manufactured such a gun, it would make the search easier. The most likely American manufacturer would be Remington but many rolling block actions were also made in Europe where the 28 gauge would be more common, I believe. Of course, any competent gunsmith could convert a Remington rolling block military rifle into a smoothbore shotgun. In fact, if one were chambered for something like the 55-100 Maynard cartridge, a 28 gauge shell might fit.