You could find out how consistant it is by pulling the bullets on a sample of factory rounds and weighing the charges.
I am pretty sure that most factory rounds are loaded by volume.
Although I may be wrong.
Ted
Ted is right. You could probably weigh the whole cartridge and get a pretty good idea. 2/10ths of a grain. Naaah, I'd bet not. But don't really know. Also, which cartridge? 2/10ths in a .300winnie wouldn't be much but in a Hornet, it's a lot.
Since the powders in most factory loads is non-cannister it really doesn't make much difference, except as a matter of curiousity. The only I've ever checked looked like 4895, but when I tried to duplicate it found that it wasn't.