RE: old powder?
I'll go one better. I have loaded and shot the rusty looking powder. But the "rust" really gooked up my powder measure. I finally dumped it. For the layman, I think the rule of thumb is, "If it looks like gunpowder and if it SMELLS like gunpowder, shoot it." Just be aware some powders naturally smell differently. A lot of the Hercules powders smell sort of like "black pepper" to me.