I know this is an old post but I thought of throwing my 2 cents for the future readers of this thread.
As far as I know, milling/polishing rice is a very time consuming task. The higher the polishing (=lower % such as 30%, 23% and such), the more time is needed progressively. For example, one sake maker in Japan claims that polishing from 25% to 23% takes 5 hours, and that's after spending 144 hours to polish from 100% to 25%....so it takes total of 149 hours!!
Now, my intention is not to discredit the effort of the original poster since many Chinese suppliers do oversell their products, but rather to inform you that polishing rice is not an easypeasy cake walk.
It's also useful to note that most milling machines for rice aren't made for milling rice for sake. In the case of Japan, most rice mill manufacturers offer machines specifically made for sake rice milling to achieve uniformed highly polished rice.
That said, I'm not sure if achieving a very highly polished rice with a regular milling machine is impossible. Maybe it is possible with enough time....for the love of good sake, does anyone have 100 hours of free time on hand?