The sizing dies I was having major issues with were the .323 and special order .325. For some reason no matter what kind of checks I used, they would get mangled. It seems that both of these dies came with egg shaped pusher stems. Listening to some of the advice here, I have had some better luck. First, I lightly lubed the heads with the pump bottle version of Hornady's one shot case lube that I had lying around. Next step, I ran the heads through the sizing die w/o the checks. After they were sized, I installed the check by hand and then ran again through the die. I found that the copper checks went on right with no issues. No matter what I did the aluminum ones still got caught up in the die and got wrecked.