I've got a .357 Herrett in a 14" Contender. I bought a Lyman medium "M" die to expand and flare the necks for cast bullet loading. Currently the load is 9.0 gr of Unique, std LR primer, and a 158gr cast bullet. I have no idea what the velocity is but they shoot well. My starting load is 10% under .35 Remington data from the Lyman Cast Bullet Handbook.
Next up will be 148 gr wadcutters, I use them in my 357 Mag as plinker loads so it'll be double duty if they work.