Home Forums Reloading Big Game Rifles Rcbs chargemaster quirk

Was rolling some ammo today and using my chargemaster set up. It would meter the charge, and many times when I opened the plexiglass door to grab the pan off the scale, the charge weight would change .3 grains. Close the door and it would go back to the original weight. Re zeroed it 2 more times. Still doing it. Also, my pan has always weighed 158.1 grains when I zero it out. Today I varied from 159.7 to 160.1. Is my system screwed? Or crazy atmospheric conditions. Only a couple years old. And been extremely careful with it.

That is pretty strange but I've never had a problem with mine.

I close the cover on mine when it's not in use and leave it open till I'm done when loading though.

How do the loads compare on a manual scale?

I don't have a manual to check them against. At this point, wishing I did. When I bought all my stuff, I went as automated as possible. Guess this is the problem.

Might be static electricity. Wipe the unit down with a Bounce dryer cloth. Found out about this ~10 years ago.

You should get a check weight set regardless of whether your scale is a balance beam or electronic. It's the only way to verify your scale is reading correctly throughout its range of measurement. RCBS and Lyman both sell them. But unless you have a lot of moving air in your room, see no need for the plastic cover to be closed while weighing or dispensing like colodog says.

Static electricity might be the culprit as lynntelk noted. You also don't want too much change in temperature. The circuits might be relatively resistant to drift with temperature, or compensate for it, but may not for large fluctuations. For instance, as an example, not a good idea to calibrate and then have sunlight shining on it if near a window an hour later. Not saying that is the case here, but an example of how temperature could exceed the circuit's ability to resist drift due to temperature change. So if you turned the heater on after calibrating, it would be best to re-calibrate at the new temperature, not just re-zero. Another thought, however unlikely, would be to check for possibility of dust or debris in or around the load cell beneath the weight platen. Perhaps some stray powder kernels.

my chargemaster fluctuates when the air conditioner runs notably, not so much with the heater same ducting, I was thinking either moister air or just heavier denser air due to temperature ??? I used to use the shield but got tired of messing with it, now I just wait for the air flow to stop or turn it off altogether

Static is a distinct possibility. I was loading h335, so tiny kernels. I brushed them away with a small paint brush, and noticed them scooting away from it on their own. Also could have potentially gotten underneath the pan holder. I will wipe down with dryer sheet.
Temp is stable and I close the air duct in that room. Window faces north so no sunlight. I'm thinking static. Thanks guys.