Tamid,
For rifles, that sort of variation is critical. We weigh every charge so that minimizes the impact but, yes, a new lot of powder can matter a fair bit. When we find one that works we go all in.

For shotguns, I'm not sure that variation becomes critical. Maybe these generic figures work okay. But with all the granulations and formulations, and then using that guestimate to jump to an entirely different powder - seems challenging at least.

Decades ago, I shot Pyrodex because I did not know anything about black and Pdex was available locally. I still have a can sitting on a shelf, never to be used. After using the real thing, I would never go back. It is not hard to buy blackpowder via mail order, but I did not know about that so long ago.

I tend to use the odds and ends of various lots of Swiss powder, when I am loading for shotguns. I weigh out 80ish grains and see how it does, then try a bit more and try again, until i find something that seems about right. Not very scientific, but it works for me. I do not shoot a great amount of black in shotguns. I save it for cartridge rifles.

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BrentD, (Professor - just for Stan)
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