I have used the powder extensively on 357 Magnum Lite, i.e. 357 cases and 38 Special performance. I have to push it to 7.0 grs to clean it up about 90%, else I get unburned powder. I have gone to magnum primers also, again trying to get more complete ignition.
Reportedly, this powder is going to go away. I have planned to go to AA#7, assuming I can get more than the one pound I have now. W231 was too soft a load, and others would work to a point too, no doubt.
What I was looking for in finding SR4756 was a powder than ran at lead velocities but filled cases enough to see powder when loading. Thus I was looking at VMD and charge weights to calculate CCs of case fill.
Actually, today I will be test firing 7.0 gr of HS-6 with 158 gr LSWC. It is not a good case fill though, so I am using the Powder Cop die until my Lock Out die comes back from RCBS with a new spring.
Now that I am better acclimated to recoil and forced to use a better grip on my guns, I will probably just go with A2400, sitting on 4 pounds of the stuff.