I read where someone ram 30-30 cases Through the 357 herrett dies to form the shoulder then loaded it with 30-30 bullets and fired them in his herrett to fire form the brass. Until this I never heard of such. I guess my question will this work.
Ummm...you had it right until you got to "....30-30 bullets..."
I loaded for one a number of years ago, for a Contender. You do start with .30-30 brass, although you could also start with with .375 win brass. Run through the sizer/case forming die, to size the neck and push the shoulder back. Trim cases to length. Run a load that is ~10-15% below max. Seat bullet (a .357 dia bullet) to the rifling and fireform, to minimize case stretch.
After fireforming, neck size, or at least back off the sizer so it does not push the shoulder back. Then it's just load development.