I'll give it a try.
Shot can be trying, in a cylinder bore. Generally a square load, same measure for powder as shot - stricken measure.
If changing, then more shot than powder - stricken.
Takes a lot of pattern work, sometimes. Some have best luck with using thin, overshot wads between powder and shot, then
one over the shot. Heavy wads between shot and powder oft times blows the pattern due to muzzle blast blowing the wad through the
shot cloud, making donut shaped patterns.
Round ball accuracy at 50 yards can be from (in my experience) about 3" to 10", depending on the gun and load - experimentation is needed,
sometimes years of it. I still havn't found a good 50 yard and further load for my 20 bore - had it since about 2006. Lots of guys have better
luck than I have experienced (it sounds like, anyway). The gun that shot 3" for me, was the one Taylor owns - a 20 bore Pennsylvania flower.
I know of another Penn. fowler that seems to shoot just as well - maybe better. That fellow uses a .595" ball, .020" ticking patch and 85gr. 3F.
He doesn't have to wipe at any time during a day's shooting. None of us do as we all use tight combinations (up here in the bush).
I have seen some decent shooting at gongs, with a 24 bore (.58), however I have never seen good 'groups' shot by one of those. I have never
seen ANY groups shot with EITHER a 24 or 28 (.54) bore.