For a box of 50, I'd load 10 rounds at X, 10 rounds at Y, 15 rounds at Z and the final 15 rounds at A and shoot your groups of 5 and see what you see.
Don't worry about vertical at 105 yards, but look for group size. That gives you 10 groups 2, 2, 3 and 3, so you should start to get a better...