Your model 65 was design to shoot 158gr ammo at about 1100 FPS. I have a model 66 and I shoot ammo that is higher than 140gr and between 1100 FPS and 1250 FPS. This is with a 4 inch barrel like yours. You can probably get away shooting 110gr stuff but I would shoot about 20 rounds and that's it for a range session. You can shoot 357 ammo in a K frame magnum like yours but watch the ammo. Stay with the above recommendation and keep the forcing cone clean as well as the top strap area.
Good luck,
roaddog28