I find powder charge size is the least critical component of reloading - I just use a cheap little Hornady beam scales to initially determine charge weight then fill the cases with a rattly old RBCS unflow powder dropper that I bought from here for a few quid. The powder drops seem to vary quite a bit by about quarter of a grain or so but in my rifles any difference it makes to accuracy is dwarfed by other factors, like wind or my my mediocre shooting skills.