Based on my limited experience-- powder type, followed by charge weight, then bullet type/weight determine which loads group well and which don't for me and my gun.
A load that works well for me is one where I see 4-5 sequential charge weights shoot moa or better at 100 yards. Each charge pretty much groups the same. For example, I'll shoot 50-51 grains in .3 grain intervals. This tells me the load is supposedly stable across this charge range, so I pick a charge in the middle.
I wasted a ton of time and powder using 4350 and barely got anything to group. Then I switched to 4064 and saw groups in the manner I just described. 4350 grouped at max charge or higher but I didn't like primer and case signs I was seeing.
I'm going for moa or better and stability though. I'm seeing .5 moa, some rounds touching, and that more than good enough for hunting to 300 yards. I want a consistent, stable load that'll always shoot moa or better.
I just didn't see this until I switched powders.
I'm also seeing amax spread of 20 fps over 10-15 rounds.