Buck13: "..so fine-grained that they slide through the gaps, making the measure harder to turn and sprinkling slowly out the side.."
I agree. Most folks complain about measuring coarser powders, but I've used several types of measures, and have had more trouble with the very fine powders than the larger granule types. It seems there's always one that wants to bind or leak rather badly. In my Lee adjustable, it's H-110, which I love for heavy .44 loads, so I just live with it. Funny, H110 looks almost identical to A2520, but that flows beautifully. At any rate, W231 is very good all around .38 powder.