When I am dealing with fired casings I do what I have to to prepare one for loading and take that first one and try to chamber it.On pushfeed bolts that is simple.On controlled feed you must start the case up from the bottom and get it in place on the bolt face.If it chambers,ok,if it doesnt I set the full length die so the bottom touches the top of the shell holder and resize one case.I try to ghamber that case.It should chamber.I would bet my eye teeth it will chamber. sam.
All brass springs back after full length resizing.Some more than other.Military usually is worse because it is thicker,stronger.You can polish bottom of die and shell holder or lightly grind both and mark them for other brass.When I say lightly grind that is what I mean.It doesnt take much to take care of the spring back.This is not a quick fix.I have seen lots of highly experienced reloaders do this.Especially on .308/.30-06 mil.. sam.