if You are running Winchester 357 Mag 158 Grains at 1830 fps(Strelok Pro numbers, from a 20" barrel), and you have a Taget Radius of 1.5" then MPBR is 125 yards, Recomended Zero 106 yards and Near Zero 15 Yards.
That is, with a Sight Height, of 1" (Guesstimate for open sights)
I use Strelok Pro for this type of calculations.