The 1851 was in .36. The “navy caliber.” The Paterson was offered in a couple optional calibers including .28, .31, and .36 but the 1851 or “belt revolver of Navy caliber” was always .36 as far as I know. That’s not to say that post cartridge smiths may not have converted some into .41 rimfire or something and I bet there were one or two out there.
And of course the modern fantasy Navys in .44 but those don’t count if you’re talking historically correct.