mbatten,
I just watched the video Parabola suggested and using "jury rigs" as I usually did will likely stop. I am changing the way I do things, except when I only need a few rounds for a "new" caliber. The source for molds cited in the video has the answer for 380, 360, 320 Rook as well as .310 Cadet and many other heeled bullet cartridges. I won't likely use black powder in my rifles, but understand why others do and I don't argue with their reasons. If you use the heeled bullets and the .375-378 ones won't chamber in your rifle, you should lube/size them to about .368" before you seat them. If you already have 38spec/357 mag dies, you should be able to use them and only need to buy the adjustable shellholder and factory crimp die.
Mike
