I have found 3f Old Eynsford powder to burn cleaner than Goex. I understand it is because they use alder wood for the charcoal portion of the black powder mix which burns much hotter than the poplar wood used in goex.
Other than Holy Black I'd say Black MZ is the cleanest I have ever shot. When sighting in my investarms .58 hawking like rifle for elk season I never Swiped or cleaned and shot 20-30 times an outing.
Elk season sucked BTW, full moon, forest service elected o do "prescribed burns" all over my unit then the joys of Hurricane Rosa. I had 1.5 days of "huntable" weather and saw one HUGE bull and heard a bull and some cows about 30 yds away. The elk have moved into the terrain described i all hunting articles, steep, thick hard core....