The weight of the shot per square inch to be moved, coupled with higher pressure, shows why deformation is more likely the longer the shot charge is in the bore.
Assuming the same shot charge in, say, a 28 or a .410 vs a 12ga, there's another reason why there may well be more shot deformation in the small bores--although it's less true now than it used to be. That's because of the significant difference in profile between a given shot charge in a small bore (relatively long and skinny) vs in a 12ga (relatively short and fat). Long and skinny = a higher percentage of the pellets in potential contact with the bore vs a lower percentage in a 12. Much of that negated by modern plastic wads, but I expect it still has some effect on deformation.
Re Brister's work on shot string, it doesn't show up to any significant extent other than at relatively long range (40 yards or more). But he points out that soft shot (thus more likely to deform) is a contributing factor.
Last edited by L. Brown; 06/06/16 10:43 AM.
