Hmm...I've thought about making a disk for the Lee, using a counter bore and bushing setup like Walkalongs Hornady pistol. (I've never seen these, no longer available?) Perhaps the bar/bushing combo would be 1/2 height of standard Lee so the holes could be larger for any given volume. For small charges of a given powder (type) there must be a practical limit as to how small a diameter hole will prevent bridging. Using a hole slightly larger than that minimum, the volume could be varied by then using a counter sink of varying depths. I theorize it's possilbe to create bushings in .1gr increments this way, but I'd also theorize an unpractical quantity of bushings would be needed. Further, made from aluminum, bushings could be coated with some of that super slick stuff on non-stick cookware. I know that powder does not stick (static) to my Satern aluminum funnels.
Oh yeah, these bushing would be much easier/quicker to change than the current disks. Insert a case, raise the ram, pop out the bushing. No more hassles with taking the measure apart.
Unfortunatley I no longer have access to the machinery needed to make such a device, so someone else would have to run with it and let us know how/if it works.