/diy/ - Do It Yourself

I'm looking to design a bullet sorter which can sort bullets up to a 0.2 gram weight difference. I have access to Arduinos, 3D-printers and a small fabrication shop, and I know there are load cells available for the Arduino that could be accurate enough for this project. My gunpowder scale needs calibration every time I use it though - how do I even begin to implement such a feature on the Arduino? I also can't seem to think of a way to load and unload the bullets from the scale automatically, I just want to build a machine that I dump a box into, and it spits out several boxes of nicely weighed bullets while I go and do useful things instead of measuring bullet weight one at a time.