PBH
Just ny thoughts mind ya, so it doesn't carry a lot of weight... but as to your question?
Another thought is how does a lighter bullet in a sabot make more pressure than a heavy conical?
I believe in some instances this really could happen, and probably does happen on more occasions than we would want to know about, but, and probably not by a veteran (and that is a poor word but you will get the idea). I have seen people insert a bullet into a sabots and then actually pound the combination down the barrel with a mallet, piece of wood, or some such thing.... that combination certainly could build up some un-wanted pressures...
Again it goes back to common sense and paying attention to detail.