I had a similar idea, but not quite as inovative as yours. I took a scrap piece of mahogany, left over from replenishing a boat, drilled three 1/2" holes, in a line, and pushed three patched .490 RB's through until about 1/3 of the ball protudes fron the far side. This centers the ball in the bore nicely. I have gotten three plastic test tubes, used by veterinarians to send in blood samples for cattle. I found rubber stoppers, shaped like corks, that fit the tubes, at the local hardware store. I keep those tubes, each filled with a pre-measured load, in my shirt pocket. I then pull the stoppers with my teeth, pour in the powder, then center the speed loader over the bore. Reloading with this set up is fairly quick.
