In my research, I did see that certain powder measures were not safe for black powder due to risk of static electric discharge. Why that is not a problem with smokeless powders, I don't know. In particular, the instructions with my RCBS ChargeMaster 1500 Powder Scale and Dispenser state that it is not "suitable" for black powder. I "assume" it is the plastic parts. That said, if you google "Harrell's Precision black powder measure", which some consider the top of the line, some of them have a plastic container. So it may be the type of plastic. Perhaps some more experienced black powder reloaders will know what the issues are.
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