The way I understand "downflip" is that the barrels flex down, at the muzzle end, when the shot is coming down the tube. To compensate for this alleged tendency to shoot low, the combs are made higher than an O/U or a repeater. The alleged reason that smaller gauges are said to do this more is because the smaller tubes can "flex" more than larger bores.
Do I believe it? Well........... it could be just another load of apcray used to fill a monthly column. Chris Batha has written about this subject recently. It's easy to accept that Chris knows a lot more about shotguns than I do.
