Lot to lot variation is pretty common though not to the extreme some have mentioned here where they're seeing 150 fps more MV at the same charge weight. Varget is notorious for two lots being pretty significantly different. H4350 and RL16 have both been, in my experience at least, pretty consistent. For the magnums, I've had pretty good luck with both Retumbo and H1000I just picked up some Rl16 to try my hand at loading 6.5CM for a new rifle. is this something that is typical of powders in general or this powder specifically?
BTW @ Lunchbox27 what is your barrel length?