A Black Wildebeest I took with my T/C Contender with a 10 inch 357 Herrett barrel using Hornady 158 gr. XTP HP bullets over IMR 4227 using CCI 250 (large rifle magnum) primers. Mine shot best toward the upper end of the recommended load in the Hornady manual.
My procedure for making cases was:
1. Run 30/30 cases into a 357 Herrett full length sizer die. I didn't use any special expander.
2. Run the formed case into a trim die, cut off with a hacksaw and file smooth.
3. Chamfer case mouth.
4. Load and shoot. I used no special fire forming load.
The 30/30 case is, relatively speaking, fragile since it was originally designed for low pressure lever action loads many decades ago. Some, I believe, use 375 Winchester brass to make cases since this brass is stronger. It's also possible to buy already formed brass from Quality Cartridge but it's pricey. Since it's a rimmed case, it can headspace on the rim but, you should improve case life if you size your cases to headspace on the shoulder.