Mr.Beck, if you use a Mec 600jr they can be found at gun shows for less than a 100$ - a new one for about 150$. If it's a used 12ga and you're going to roll crimp all you'll need to use the 600 is a different resizeing ring [ or don't resize and take the 12ga ring off ] . You can deprime, prime, and add the powder, wads, and shot with a 12ga set up. Then just remove the shell and roll crimp. Or buy a 10ga and make a spacer the proper height to go under the plate for crimping. I like 19grs of 700X and plastic or paper wads [ from
www.circlefly.com ]. Tell Craig what you're doing and he'll set you up. Paul