That's really not true. Modern shot cups protect the edge pellets from rubbing against the bore, getting flats, which become huge sails to stop their forward movment, so they drop out of the pattern quickly. BP shotgun loads have trouble because they are not choked, and if they are, they still don't protect the shot from being misshapened in the barrel. Worse, lead is deposited along the barrel from the lead that rubs against it.
FFg powder is a better choice for some large gauge guns because it does burn slower, and does not hit the shot so hard that pellets are " kicked " out of shape, when the gun is fired. That does not seem to be as much a problem with the smaller gauges.( 24,& 28) I suspect that occurs because there are so few pellet on the outer edge in these smaller bores, shooting the normally lighter loads of shot.
In the 19th and earlier centuries, all lead shot was soft. Today, we have shot that has antimony in it( Magnum) and even plated shot, Nickel and Copper, which both resist pellet deformation and the leaving of lead deposits in the bore. But, even these harder LEAD shot examples produce much better patterns out of a cylinder bore gun if they are protected by a thick shotcup, made of plastic, or some other substance. That is why you see so much experimentation being done by members here with various kinds of paper shot cups.
My own experiments with my 12 gauge indicate that the paper cups will produce tighter patterns, and if I play around with the loads some, I may be able to get better than 45%, or low modified patterns out of my cylinder bore gun. This would be a substantial pattern improvement over what is normally delivered. I have not yet tried coin wrappers, or card stock, but they are on my list of things to try. I do know that the secret to better patterns with more shot in them, is to use less powder rather than more. That seems counter intuitive compared to what works well in modern guns, shooting smokeless powder and plastic shot cups and hard shot.
A friend of mine experimented, for instance, with the then new Olympic Trap load, which are 3 1/4 dram Eq. and 24 grams of nickel-plated shot( #7). Those loads are screaming out of his full choke barrel. He was getting, on paper, 98% patterns, and all his shots were delivering patterns in excess of 93%. Those are superb patterns out of any shotgun, and he could break clay targets all day with those rounds. I think they were way to expensive for him to use on dove, so I don't have a report on how that kind of load works on game birds. With that much of the shot staying in a 30 inch circle at 40 yards, the number of pellet hitting the bird had to be almost double what we would normally expect at that range. When you take into account down range pellet energy, those extra pellets hitting a bird are probably more than enough to bring the bird down hard.
Its too bad that BP shotgun ballistics don't work that way.
I do think that if you lubricate your shotgun bore with Bore Butter, or Moose snot, after you seat the OS cards, that the reduction in friction will leave more pellets round, and less lead on the bore to spoil subsequent patterns. It is clear however, that the continued build-up of lead deposits on the bore is a major contributor for increasingly poor patterns out of BP shotguns. When the bores are brushed between shots, and cleaned using lead solvents, patterns become much more consistent. The folks who shoot the chrome plated shotguns are finding that they have less problems with pattern deterrioration, and that the bores are much easier to clean, both between shots, and at the end of the day. BP residue just does not seem to get a good hold on a chromed barrel.
You might all consider some of these ideas during the off season.
