[Unclenick]

Using a powder that is too slow reduces the chamber pressure, but powders burn more cleanly at higher pressures. As a result, when you target a certain velocity, using the lowest pressure load that gets there isn't always the best idea. The highest pressure load that produces the desired velocity (typically from the fastest powder listed to produce it) will usually be the cleanest burning. It will also often have the smallest charge weight and that will result in the lowest recoil for the desired velocity.

Ball powders, except very fast ones like 231, also often have trouble lighting completely without a magnum primer, so that is another consideration. In rifles the smallest load that produces a desired velocity is not always best because it may not fill the case well, which causes ignition inconsistency. Most handgun cartridge cases are so small that case filling does not typically matter, though.