I'm hunting for a good powder too ...
My test gun is also "powder sensitive" and binds fairly regularly with many of my experimental loads.
Shooting 158gr LSWC in loadings from light through +P, I find
BULLSEYE is dirty at lighter loadings
CLAYS is wonderful, not a spec drops out of the fired cases, for all loadings
HP-38, apparently made "expecially" for this caliber. is dirty throughout the entire load range, big disappointment
UNIQUE shoots very well in all loadings but is dirty as all crap, but I expected this
If you shoot lead, one issue you might profitably watch is the bearing surface of the yolk tube which projects down the center of the cylinder at the point where it joins with metal hinge piece that slides into the frame and is locked in place by that screw. i recently found there much accumulated LEAD, which I'm sure made my gun much more sensitive to any buildup of additional crud than it might otherwise be.
To date, Clays and Unique are my most consistently accurate powders, go figur . My leading problem here seems due to large throats (.359+") in this particular gun. I have been shotting 0.358" but I think most buildup was from the 0.355" (pulled from factory) i shot previously. Forcing cone periphery was "plastered".