Hope this is the right place for this question. I have a Thompson Contender in 30 Herrett and had no brass. a search revealed that you had to buy separate forming dies. I lookied at my RCBS sizer and it looked like it would allow me to set the sholder back if I pulled the top off the die. So I did, ran some 30-30 brass through it and I seem to have 30 Herrett brass that can now be fire formed. When I make 22-250 brass I have to ream the neck. It does not look like I have to do so with the 30 herrett stuff. Am I missing anything here. I don't see why I would have to buy a separate form die. But I read on several sites that you can't do what I seem to have done.