The problem is really that the grains are unpolished and still have a layer of bran on them - they're the brown rice equivalent of millet. I can buy white rice, but not "white" millet.
The solution is to use more power.
My food processor has two blades which looked reasonable to use. One is the regular cutting blade (note that Cuisinart recently had a blade recall, which affected mine), and the other is the shorter-armed, plastic dough blade.
I tried both, for sixty seconds continuously:
I soaked 3/4 of a cup of the polished grain for a few hours and it expanded to 8 ounces. Not the dramatic near-doubling that rice does, but still it's something. Soaking overnight didn't give it more volume.
Post-cooking, it's definitely better than before:
During fermentation, there's still a lot more bulk than with the rice, which I think decomposes more fully so maybe I should investigate other strategies for polishing, but this is at least a start.
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.