OK, that explains a lot. 55years of handloading, and still learning. (Me BTW).Also, if you look at Western's data for Accurate ball powders, they published the only bulk density specs I've ever seen, some of which are up to ±5.6%, or 11.2% extreme spread.
Many years back, when my first .35 Whelen came home, I snagged a pile of Remington .35 W brass. Still using the same brass, and have lot's of unfired in inventory. Good stuff, but it doesn't hold the amount of powder listed in many sources. Used to wonder why. Old too soon, smart too late