You know this is a LOT of fun and your enthusiasm is pretty obvious too. All I have ever seen was text refs and a few black & white drawings of some purported attempts to improve matters from the cut 'nails, gravel & wasp nest cannon fodder' muzzle loader era. Folks were thinking and doing early on during the industrial revolution, but as you so correctly observe, not much remains that is absolute or that one can hold or even actualy touch and examine. Perhaps the nearest doc's office would accommodate an X-ray image for you? Glad that you captured them and will be most interested in any neat developments or revelations forthcoming. To get that fine gun back in action would be a very nice accomplishment, aside from proving your thots to be correct.
Seems to me that somewhere I also read of or saw a drawing of a 'cartridge' [shot column] that was contained in what was more like a modern silk lantern mantle than anything else from a description perspective; the idea again being to assist pattern density I thot, but perhaps that too was actually a method of convenience for the user. I don't know.
