If you really want to drive yourself crazy, I had Clifford Noll build me a replica Ferguson Rifle about thirty years ago. He was up in Northern Idaho last I heard, but that was a long time ago, like late 1980's.

Yes, I have owned them and fired them; usually without the paper cartridge as it is just easier to push the bullet in with a short rod and dump powder in behind it. My Pedersoli 54 rifle chamber holds about 120 grains of powder, so I use a fiber wad behind the bullet. I made the late type paper cartridges out of paper, and gauze for the back end; not the early cut off type. The breech gets sticky after a few shots.
Idaho, do you still have the Ferguson? I have always wanted to build one but I can't figure out how to thread it. CNC would do it easily but I ain't got one.