Your findings are correct. Large crystal powders (like Unique) and large flake powders (like Red Dot) do not meter especially well in anybody's powder measure. These are older design powders, and you'll have a much easier time with more modern powders.
Suggestions...
• Swap your
Unique for
BE-86 which has the same burn rate, but meters much,
much better.
• Lube your empty powder measure with a squirt of
powdered graphite into the hopper, especially when the measure is new. This stuff is available in the Lock section of your hardware store. (Graphite is already applied to most smokeless powders, you're simply speeding up the transfer process.)
• Find some office rubber bands that fit around the neck of the hopper and then onto the teet on the end of the Powder Bar. New Powder Bars sometimes need help retracting. This extra "help" will settle the powder more quickly, and thereby give you more consistently accurate powder drops. (Older Dillon powder measures actually came with a spring in this position.)
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Hope this helps.