Guys: You have to use at minimum a overpowder wad, so that gases are sealed behind even this package, and more importantly, the shot leaves the barrel at the same time. I like using a smaller gauged overshot card in the bottom of my paper shotcup to give a smooth, hard surface to push the back end of the shot column as it leaves the barrel. The overpowder wad keeps the gases from blowing through the shot column, or escaping to one side or another as the shot leaves the muzzle, thereby destroying the pattern, but doing so differently with each shot fired, so that you can't learn much at all from examining patterns on a pattern board.
A final thought we should all consider: modern shotgun shells and components are the cumulative result of all the years of research done, first with black powder muzzle loading shotguns, later, with black powder cartridge guns, and now with smokeless powder cartridge guns. If it works in a modern gun, it probably will work in a muzzle loader, PROVIDED the demensions of components are correct for the actual barrel size. If you can find the older paper hulls used up until about 1955, and examine the fiberwads, and fillers, and shotcups, like the old Alcan cup that has been discussed, you get a pretty good idea of what will work in your muzzle loader. New products come along, like styrofoam, which may improve performance, and should be considered and tried, but the older components also work. There is almost no reason to attempt to re-invent the wheel.
When working up loads for my 20 ga. fowler, I found that the loads that gave the best patterns were the same loads used in modern 20 ga. shotgun shells. I was not surprised.
