Hmmm...it'd be a real bitch making, but I wonder if powder could be dropped more accurately like the big manufacturers; via volume and vibration. I'm thinking a rotary disk with cups (almost like a shotgun reloading charge bar, but round), so that the cup could pass under the powder column several times before being dropped. Each indexing of the rotary cup would cause the powder to settle more uniformly.
Just thinking out loud here...
And it goes without saying....that's an AWESOME set up!