Here is what works for me in my GP-100 6" barrel:
1. 158 gr. Laser Cast Round nose flat point, Winchester cases, Winchester small pistol magmum primers:
5.7 gr. Hodgdon Universal, 1.560" OAL
High: 1089 fps
Low: 1061 fps
Average: 1076 fps = 168.39 power factor
Second String same load:
High: 1098 fps
Low: 1035 fps
Average: 1081 fps = 169.2 power factor
OR
158 gr. Laser Cast RN Flat Point, 1.555" OAL
5.4 gr. Titegroup
High: 1141 fps
Low: 1108 fps
Av. 1122 fps
175.93 power factor.
Knocks down poppers without hesitation. However, Titegroup is a faster powder than Universal and gives a sharper recoil.
OR
158 gr. Rainer Copper Jacketed Flat Point
5.9 gr. Titegroup, 1.590" OAL
High: 1094 fps
Low: 1072 fps
Av: 1081 fps
170 Power Factor.
A clean load if your revo likes copper plated bullets. Also seemed a little sofer than the Titegroup lead load described above.
158 gr. Laser Cast RNFP
6.5 gr. VithaVouri N340, 1.555" OAL
High 1153 fps
Low 1117 fps
Av: 1142 fps
Power factor 178
FWIW:
My preferred load now is a 140 gr. lead flat point that has a little less muzzle rise than the 158 gr.
140 Laser Cast or Mid-Kansas flat point.
Winchester or Starline cases, Winchester Small Pistol Magnum Primers
6.2 gr. Hodgdon's Universal, 1.577" OAL
String 1:
High: 1264 fps
Low: 1211 fps
Ave: 1230 fps.
String 2:
High: 1254
Low: 1200
Av: 1220
Use round nose or round nose flat point bullets for faster reloads than with semi wadcutters. I'm glad to see someone besides me is using a .357.
Good luck and stay safe.
Chris