I weigh all my charges too, currently running a 10-10, nice scale. Not sure if they actually go bad, but I think over time my 505's dampening magnet got funky.

On aside, I make a slug out of steel rod that weighs the same as my powder charges. Periodically I place it on the pan to check my "zero". This has been the easiest for me to make the check without constantly setting the scale back to actual zero, which is a pain in the ass to break stride during a run.

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