All handguns are individuals and have preferences. I don’t have a Model 59, but your feeding issues could be a slightly rough feed ramp. You might want to look up someone who works on old Smith autos and see what he says. Novak in West Virginia (304-485-9295) has worked on my 4506 and 1006 and might work on a 59.
My first handgun was a 6” Model 27-2 in 1974. It is the same as the Model 28, but with the deluxe finish. It is a pretty beefy .357. Mine hasn’t been picky about what it shoots well. For personal defense, 125 gr. loads seem to be the preferred answer. For inexpensive practice with factory ammo I like to use the 158 gr. CCI Blazer. It is a little milder than many factory loads and shoots well in all my .357s. I would stay away from the older style lead ammo loaded to full performance velocities. I can remember years ago leading my 27 pretty badly with that stuff. Cast bullets with mild loads shoot well in my guns and won’t lead things.