I have used SR4756 in my 32-20 handguns since I first read about it in Ken Waters' book. I tried it and it worked better than the other powders I tried, even Unique. It works best at stiff loads.
His load was 6.0gr with a 100gr bullet. I don't remember if his was jacketed or lead. I use it with jacketed bullets or a lead gascheck bullet (Lyman 311316). Both work great. I use a little less powder with the heavier bullet (5.8gr). These loads are stiff for a 32-20 handgun, especially one as light as a Colt PPS. It is OK in a S&W K-frame or single actions. SR4756 does not work well with light loads. When you get down to 5.2 or 5.0gr, it is inaccurate. The velocity appears to be fairly erratic at low loads. For light loads, I use Trail Boss now.
I have not tried SR4756 with plain base cast bullets. It would probably work with a hard mix (Bhn 15 or more), but I doubt that it would work with a medium or softer mix.