Re: Powder scale
If it's for powder, you don't need .01 grains accuracy. I run an Accu-lab 123, and it's good to .02 grains. It is sensitive to a kernel of gun powder (less than a kernel depending on which powder). Battery powered, I don't know. I've read you get variations in power from batteries, which keep it from being highly accurate.
The only battery powder units I know go to .1 grains, which would be fine for field use. If it's to be used in the field, you might find that other external factors will be more of a problem than the scale, like wind and level tables and such.