What I have used for max vel loads in the past. These will do about 950-1000, which is what
the 125 Rem is spec'd at. No special reason. If TG will do the same POI and reasonably good
velocity, that would be fine. Never noticed flash with PP, but never tried it at dusk or dark.
OK, I checked and 5 gr of TG will do about the same, so may do that.
231and Bullseye would be good as well. Not much that won't work well in a .38 with light bullets. Titegroup burns really hot on the high end, you can tell by the rate at which the cylinder and frame heats up compared to some other powders. If you're going for smackdown loads, I think you'll like BE-86.
Little late here but the lighter bullet always hit lower for me all things being equal. As for faster vs slower. The slower bullet hit higher at 25 yards. Can't speak for others but how is works for me.