One of the problems you are encountering is you are trying to crimp a bullet without a crimp groove. Berry's #84525, the bullet you are loading does not have a cannelure, or crimp groove that you need to keep the bullet from jumping in a .357 mag. load without ruining the bullet or cracking the plating. With a crimp groove you can put a pretty heavy crimp on a .357 case without much trouble. I believe Berry,s #72843 is the same as #84525, but with a crimp groove.