Loading slugs in brass hulls is NOT a good idea.
There's 2 types of brass hulls available today. The magtech, and the Rocky Mountain Cartridge hulls.
The magtech hulls are very thin, so the inside diameter of the shell is HUGE! Normal 12 gauge shotshell components do not fit. They're too loose! That requires the use of 11 gauge card wads for the over-powder wad. Then comes the way to hold everything together, IOW how to crimp them!
The rocky hulls are lathe turned, so they're much thicker. You CAN use standard 12 gauge wads. But again, how to crimp?
You'd be much better of using just about any plastic hull. Then you can use normal trap wads, AND use a star crimp to close 'em up. If you want to get fancy, roll crimpers are available to make them look like factory.
Lee, and Lyman both make slug molds. I have both of the lee molds, one is 7/8 oz. , the other is 1 ounce. I also have the lyman mold, but it is very heavy, almost 1-¼ ounce. Lyman also makes a forester type mold, the old hollow base round nose. It's full bore size, so it CAN'T be loaded inside a plastic wad.
