I tried Trail Boss, Titegroup and Unique in my 45 Colt Blackhawk with 200 Grain cast lead bullets and discovered the following successful loads:
1. 200 Grain Cast bullet, 6.7 Grains of Trail Boss (using a LEE Dipper 1.6) for about 860 fps, CCI Standard large pistol primer, Remington brass (fired a few times) - 1.3" groups (best 4 out of 5) at 25 yards.
2. 200 Grain Cast bullets, 7.5 Grains of Titegroup (using a LEE Dipper 0.7) for about 1000 fps, CCI Standard large pistol primer, Remington brass (fired a few times) - 1.1" group (best 4 out of 5) at 25 yards.
3. 200 Grain Cast bullets, 8.3 Grains of Unique (using a LEE Dipper 1.0) for about 1025 fps, CCI Standard large pistol primer, Remington brass (fired a few times) - 2.1" group (best 4 out of 5) at 25 yards.
The Titegroup load proved to be the most accurate, but not by much (as I found in continued testing). However, since I use LEE Dippers, I prefer Trail Boss because small variations don't seem to make any difference; and I am not as careful loading in the field.
Both Titegroup and Trail Boss outperformed my Unique load. These powders also work exceptionally well for me with cast bullets weighing up to 270 grains. This was not the case when I moved to the Hornady 250 Grain XTP JHP. With this bullet, Unique was the most accurate powder.