I have been doing some powder coating for 8 mm and 30 cal boolits and Have had trouble getting gas checks onto the shank of the boolit squarely. I , this last time , used my 225 sizing die in my press to stop the boolits and then pushed the gas check onto the shank with the 30 cal pusher. They snap on and go square without any damage.
Attachment 267891Attachment 267895Attachment 267892
I am going to apologize in case this is someone elses idea, but it dawned on me so I wanted to pass it on. The checks crimp on firmly when pushed through an appropriate size die.