Bry,
If you have a closer look at it on the RDG website (there is a button to press to see more) that shows a larger picture. The finish I obtained was almost identical to the finish on the hopper.
No use for large castings, for that I will use the big gun with very coarse grit, but for fine stuff as you are doing, it will be ideal.
You might find glass bead or even bicarbonate of soda a finer remover, it should leave a more polished surface.
If I remember, I will send you a small bag of superfine glass beads in the package I send back to you, just for you to try.
John