When I was looking for a light cast bullet load , more like the police load the model 58 was supposed to shoot, I sent a letter to Guns and Ammo with a stamped self addressed envelope, I had the Lyman #410459 220 grain SWC mould and Unique powder.
My letter was returned with " use 7.5 to 8.0 grains with that bullet " and was signed Elmer Keith !
7.5 to 8.0 grains shoots to the sights , I use a 6 o:clock hold, with the model 58 in my avatar. Try it, it works well with the following cast SWC bullets: 195 gr , 210 gr. , 215 gr. , 220 gr.
I've tried them all.

As for your model 57, just adjust the sights, that's why they are called adjustable !
Gary