Check out Dan Newberry's OCW load development
method. He intentionally looks for loads that are insensitive to charge weight over a span of 1.4% to 2% of charge or so. By loading for the center charge weight of such a load, you can use a powder dispenser that throws about +/- 0.3 grains and they will all still shoot to the same POI.
A number of powder dispensers may be acquired that throw charges of spherical propellents to within a tenth of a grain. Sticks are more problematic, because of grain cutting by most measures that upsets the powder flow. But stick powders ignite better and the coarse sticks, especially, are less likely to give you a touchy load. I like the JDS Quick Measure
for stick powder. It dispenses stick powder to within a promised 0.2 grains, and often does better than that. It's design prevents grain cutting from occurring at all, and it can be adapted to progressive loaders if you are working on a significant volume of ammunition.