A few things. Poor accuracy in a smoothbore is usually due to having inconsistency in where the ball sits within the muzzle. That's why the Bess was for more than a century considered "inaccurate". The military was using very undersized ball to allow for the buildup of crud due to the number of shots fired.
So what you want to work on is getting a consistent ball-in-the-barrel placement. One way..., you roll paper cartridges that hold the ball snug in the barrel. You have to make a "former" out of a wooden dowel and sand it down, so that when you wrap the paper around it, it just fits smoothly within the barrel. The ball must fit within the cartridge so that the cartridge doesn't flex outward, and the ball doesn't move about within. The base of this cartridge is flat, and that is the side with the ball within, that you ram down onto the powder. It's basically a paper "shot cup" and it also works for you with shot.
A second way is you get ball that is very close fitting to your bore, and try that loaded over a lubed, fiber wad, and held in place by tow, or a wad of paper, etc. IF that doesn't work for you then you get a wood rasp, and you roll that same close fitting ball between the rasp and a pine board. You want to raise a little bit of the lead on the surface of the ball. So you load powder, a wad of some sort, and then you will need to force the ball into the barrel because tiny bits of lead that you raised are now making the ball a tad too big. Your forcing the ball into the barrel swages some of that raised lead back down, and the ball is then custom fit to your barrel. Ram it down to the wad, and that should be a consistent shooting ball..., what sort of sight "hold" you need to use to hit the target, will be another factir, Some folks have reported good accuracy with loading a 1/2" wad, a bare ball, and a second 1/2" wad on top of the ball.
A third way of which I've heard, is to take an unlubed, 1/2" fiber wad, and locate the very center of the wad. You then take a large drill bit, and by hand, you create a shallow, concave dimple in the wad. Then you take a spot of something like rubber cement, and attach the ball to the dimple in the center of the wad. To load, after you drop in your powder, you ram down a lubed 1/2" wad (which will leave some lube on the walls of the barrel), followed by the ball-and-dry-wad assembly. This is then followed by something like tow, or a paper wad...., What this does is even if the ball isn't a good fit for your smoothbore, the dimple will center the ball and the glue keeps the ball from shifting when loading. Upon firing the mass of the ball compresses into the wad a tiny bit, but because of the pre-made dimple, the ball stays centered. The glue seam, however, gets fractured due to the jolt of firing, so that when the ball exits the muzzle, it is no longer glued to the wad. The trick is..., getting the dimple in the exact center. I suppose a tool could be fashioned to give you the center every time. I've yet to try this, but it would allow the use of a smaller ball that would equal higher muzzle velocity, and if you were using alloyed lead a bit lighter than pure lead, you'd get even better velocity. I've never tried this method, and..., I'm unsure which would be better..., loading the wad-ball assembly with the wad toward the powder, OR loading the wad-ball assembly with the ball toward the powder and the wad toward the muzzle, omitting the over wad or over shot card.
LD
