I do small batches ( like about twenty at a time) I run the shaker for about ten or fifteen minutes, and the sawsall for a little more. The sawsall doesn't run as fast as the paint shaker. I think a jigsaw would work as well.
In my 20 gauge tradegun I load it with at least eighty grains of 2F, drop a bare dimpled .595 ball on top of the powder, and then run a wad cut from an old wool blanket down on top of the ball. I just barely dipped one side of the wad in hot bear grease, to soften the foulings.
These shoot pretty straight until they start losing velocity. Once the velocity drops way off they start to wonder.
Hungry Horse