Dig up an original 1935 ad for the new .357 Magnum. It claimed 800 ft. lbs. with a 158 grain bullet at 1510 fps. In the Lyman 45th Edition, the "factory duplication" load was 11.6 grains of Herco behind a 158 grain cast gas check SWC. Back when I was younger and bolder, I tried that load behind some semi-wadcutters out of my RCBS mold, that actually ran about 162 grains. I averaged 1503 fps with those 162 grainers and broke 800 fp, out of my 8-3/8" Model 27. Interestingly, I averaged 1488 out of my 6-1/2" Blackhawk.
BUT: Out of two cylinder loads, I pierced primers twice and seriously cratered the rest. I'm not surprised the next edition of Lyman dropped that load back a lot. In fact, I think Lyman and the more cautious Speer settled around 9 grains.
I'm not sure but what the original claimed .357 ballistics were from a test barrel. Or maybe, with a thinner flash gap than my 70's M27 and the original 8-3/4 barrel, they really did hit the mark. I read the original loads leaded badly, too.