Among the rarest ctges

  1. A gunsmith named [b]Pi

Now that is an interesting idea, JP :-). I’ve seen what could be considered almost the exact OPPOSITE of that design in an American Civil War-era revolver called a “Conical repeater”, where a stationary 6-shot cylinder was mounted in the back end of a large funnel, and that funnel narrowed down until it became a rifled bore of the proper size. Cartridges were fired by a hammer nose that rotated around the sylinder, striking each round in turn.