The 357 mag/max, 44mag, 22jet, 30-30, 45-70 all used to be on the iron frames. It won't hurt a thing by maxing your 357... just dont go crazy with loads. If you put a 45-70 barrel on an SB1 frame stick to trapdoor loads.
I've got 22hornet, 32-20, 357mag on SB1 frames and they all shoot great.
Spanky