the cartridge must have been very similar to the military rifle cartridge but with a shot load insteed of the bullet

here you see the different military cartridges starting with a roundball in 1841

I think allways there have been some paper not completely burned in barrels what would become a problem after some shot so you have to clean the gun while hunting from time to time. it was the moment in gun history when you have to make the step from muzzle loading to breech loading firearms.