Lister said it. Forget the increment scale and go by what it looks like. When I got a popular load set, I used to scratch a little mark on the outside of the big adjustment. Problem was, after about four little marks, I forgot which was which!
To get accurate measurements it is important to use the same swing every time. That is, give it the upswing to hit the top stop, then the same speed down. It is consistancy you are after.
For very small amounts of powder, just use the two screw adjusted openings, with the big one closed tight.