I need to get my reloading press out and see but the only time I ever had this kind of problem was when I was trying to crimp handgun loads.
I did have a couple cases get funky on me when I resized from 221 Fireball up to the 300/221 but that was just a few rounds and most of those were lube related....
I do like the looks of those black heavies on your loads... what bullet is that?
I use Redding Dies on a RCBS Rockkchucker press and they are not true "Whipser" dies but instead the 300/221 clone but I don't remember having the kinds of issues you are having but I have not reloaded 300/221 in a couple years now and my mind is less then trustworthy