I think I could handle the actual loading if I had a manual that said "pour X amount of Y powder with Z primer" but the other stuff is what's confusing.

What about the other stuff like to check velocity and trajectory? How do you know where you're bullet hits at 200, 300, 400 and 500 yards? How do you know how fast it's going and how much energy it's carrying at any distance?

To me that's the hard part but maybe it's not?