I've tested a few powder measures. Oddly, one of the best I've tested is the Lee Perfect Powder Measure.
On ball powders, the Hornady balance scale has an error standard deviation of about .04 grain. So 95% of the time, you can see changes as small as .08 grain.
With 2520 ball powder, the Perfect Powder Measure is better than that. I don't know how much better, because I can't measure changes that small.
With H4831SC, the Perfect Powder Measure has an error standard deviation of .1 grain. So 95% of your powder throws will be within plus or minus .2 grains.
The Hornady Lock N Load throwing H4831SC has an error standard deviation of .14 grains.
All of these are completely adequate unless you're shooting a 1/2 MOA gun at 1000 yards. Even then, the end result is still pretty good.
