Some time ago, there was an article published on the internet relating to powder measure modification to improve the performance of a RCBS powder measure. I have looked for it since then, and cannot find it. The fellow had done a lot of work and testing, throwing thousands of charges. I won't say that he found the magic combination, but he did do some things that improved the performance of his measure.
One was to fabricate a new handle that was twice as long. I think that this helped power through cut grains without so much of an interruption in the stroke, as well as turning the operation into a more consistent arm motion, and less of a flip of the wrist.
The second thing involved the fabrication of a much sturdier measure stand. He said that he had found that all commercial stands allowed more measure vibration than was good for consistency of charges. I believe that his had an upright of 2" square tube, welded to a quarter inch thick flat plate that was about 6" square that was screwed to the bench. There was a strap of similar thickness that was welded across the top of the tube. that overhung front and back, with a hole in front to mount the measure.
The last detail was the baffle. After considerable experimentation with a number of designs, some quite involved, he determined that a simple flat plexiglass baffle, held in place by the compression of an O ring (I think) in a groove around its circumference. worked best. It had a half inch hole in its center, and its height in the reservoir was about an inch above the edge of the casting or thereabouts.
I do not use a RCBS measure, but I thought that I would provide this information for those that do.
The one thing that I would add to this is that in order to perfect your technique or evaluate equipment you need a scale that is better than the average electronic reloading scale, or untuned balance scale. I have had the extended use of a scale that read to .02 grains, and I own tuned balance scales that are quite sensitive that are useful for this kind of work.
I use a Harrell Deluxe measure at the range, leaving it in my range reloading kit, and one of several SAECO Micro-Set measures at home. The techniques that I use with them vary by powder and measure, and they did not come from an article or book, but from a lot of experimentation, from which I learned quite a lot about the effects of various aspects of measure operation.
My experience with baffles has convinced me that the best baffle is none at all, but to mark off a range of reservoir fill that works best and add powder to keep the fill in that range.
I could write a whole chapter on measure technique, but I won't bore you further here.