Try using powders like H110 and H335 thru them and weigh each charge and note the variation in the charges. The ONLY way I got any of my Dillon powder measures to throw these two powders consistently was to highly polish the powder bars. Polishing the internals did absolutely nothing nor did replacing the baffle with a larger one. As I mentioned the barrel type of powder measure does throw more consistently. The Hornady with the optional linkage to adapt it to reloader operation in my experience produces excellent results. Powder measures the older hand operated ones like the RCBS rely on the operator being able to duplicate his ability to consistently apply the same amount of force. Too much force and the load could be .1 or .2 gr heavier.