....and you said the key words there, Stepped expanders make seating the easier as they create a sort of funnel at the top of the case.
That is what lures and fools cast reloaders into thinking that M die is the holy grail and it really is not for the reasons I've explained. Hey when loading jacketed rifle bullets I love boat tail bullets as they set in the case mouths nice after you charged the case with powder. Or look at the sides divided over bevel base cast pistol/revolver bullets. Everyone is always looking for the easiest way out with necessarilly isn't the best way. Sorry for the rant, but the myth that the M die is the best must be stopped!