This one appears to me to be a breech loading percussion shotgun, not meant for any ctg. - except for some sort of self-contained, completely wrapped in paper ctg. would be possible, I assume. The ctg. would look similar to the military ctgs. of the muzzleloading era which contained powder and ball or powder ball and buck shot. In this case, they'd be powder, wads and shot. The breech extensions would have to seat well into the powder charge in order to effect ignition.