On another BP forum, several shooters report good patterns using the a cushion wad as an over shot card. Powder, OP wad, shot, then cushion wad.......robin
I cannot imagine how that would help patterns. For non-choked guns, a shot protector or concentrator like a post-it note wrapped around a wad, glued shut, then filled with shot, then rammed down as a unit, with thin card over top has worked for some people. This would be for longer distance shooting (just as they were designed for this in the 1800's) as the wad needs to fall back from the shot cloud. Out to 25 yards, it may shoot as a slug.
In my 20 bore, I use 70gr. of powder, with a 75gr. measure filled with shot. I use a hard card over the powder and a 1/2" lubed cushion wad over the OP wad, then the shot, then a thin card OS wad. This patterns about Modified in my gun which is V-nice, but this gun has a slight choke - about IMP- CYL.
That's pert near my old 20 bore recipe, only on that particular gun I could use a whole fiber wad. They are all different. The only recommendation I can make is to figure out some way to lube the bore. Most of my shooting was skeet so at least 25 loads had to be made with out pumping out the barrel.
I ran into dough nut holes with 14 , 12 and 10 bores....don't know why that is. More short barrels than long...don't know why that was either.
I think maybe there was some "Trolling" going on in those other sites. Mike - one reason could be that shorter barrels will increase the muzzle-blast at the muzzle due to higher muzzle pressure. Higher pressure and blast, will drive that heavier wad, especially a lubed wad, through the shot cloud before it gets too far from the muzzle.
The wad is driven into the middle of the shot cloud, which literally gives it a hole in the middle. This was displayed quite graphically by W.W. Greener with a "shadow graph" (early high speed picture) with a 12 bore cylinder, compared to choked gun, also a 12 bore. With the choked gun, the wad was held back a split second, allowing the shot to outdistance it.
In the picture of the choked shot, the heavy wad was trailing the most tardy pellets, the column actually a very tight mass of pellets, strung slightly horizontally, instead of radiating outwards as in the cylinder bore. In that shot, the wad was being driven through the shot column, which was spreading radially and this in only 12 or so inches from the bore, it was already out about 2", while the choked shot was perhaps a 3/4"diameter pattern.
Some guys use only tin "B" (OS) wads over the powder, several of them making for a much lighter 'wad' than an 1/8" card + 1/2" Donnaconna standard wad, lubed or not. Some guys, when loading a muzzleloading shotgun, forego the overshot wad & simply use the cushion wad, which seems to work fine in choked guns, but not well in cylinder bore guns due to the donut patterning problem.