Copied from another forum! (Cast Boolits) Use at your own peril:
Google: "Alliant, Herco, .357 magnum, load data"
Lyman 45th Edition Reloading Handbook and for the cast boolits it stated for HERCO powder:
121 gr. cast --- Min: 7.0 --- Max: 11.9 (compressed)
141 gr. cast---------- 7.0 ---------- 11.8 (compressed)
150 gr. cast --------- 7.0----------- 11.7 (compressed)
158 gr. cast --------- 7.0 ---------- 11.6 (compressed)
168 gr. cast ----------7.0----------- 10.0 (compressed) - my favorite 38/357 boolit
195 gr. cast --------- 6.0------------- 7.5 (compressed)
The authors of similar posts in the thread could not recommend loads over 10 grains for the 158 grain do to pressure signs and recoil impulse!
All the best,