I have a couple of Iver Johnson owls-head top-break safety hammerless 32 S&Ws- the 2nd model, which was a black powder model.
I load the Lee 311-93-1R bullet (6-cavity mold 90308 iirc) cast from water-dropped range scrap (bhn 12 or so) tumble lubed in ALOX, seated so that the lube groove closest to the nose becomes the roll-crimp groove.
My powder charge is IMR 800-X because I want a slower powder for those black powder guns. I don't have my notebook here with me *but* I think I am using 2.0 grains of 800-X CORRECTION: 1.75 grains of 800-X in this load!!. The load is pretty wimpy. I was shooting at an old car door. The bullet would just barely penetrate the door from straight-on 10' away and then fell into the door cavity. If I was at an angle it would ricochet off the door. That's my 32 S&W (short) load. You have a smokeless gun so you could go a bit hotter. I would start experimenting around 2.0 grains of Unique and work up from there. I would say a 2.0 grain Titegroup load would be MAX in that.
I load some 32 Longs for other guns, those do nice with 2.5 grains of Titegroup and that 93-gr Lee bullet- this is my favorite load for the Colt Official Police and other such small-frame guns. 2.5 grains of PROMO (Red Dot data by weight) was a little softer but still shot well. I also load a 45-grain #0 Buckshot pellet with 3.5 grains of Titegroup, this is a FUN load. These are 32 S&W Long loads.