I have the same powder measure. I always weigh each charge on the light side, then trickle to where I want it. Have you ever cleaned out tour measure? I did mine and it still had kernals of powder in it.
I use mine for three different powders, IMR 4350, Unique, and R-15. I noticed that there is still unique powder trapped in there. Not much but some.
As the others have said, stick powder does not flow well in this measure. At times Unique will be way off also. Now I just set it low, and trickle in till I get the desired weight. Takes longer, but I'd rather be safe, then sorry.