So its consistency mainly?
I watched a special on snipers and they were talking about the ammo that is used. IIRC they weighed and measured each piece of brass and each bullet. Each powder charge was measured and finished with with a trickler (sp) one speck of powder at a time. Then they were hand loaded on a single stage press, measured and weighed again. Then they were placed in a plastic box with foam compartments to stop any dings on the bullet. Each plastic box was labeled with the serial number of the rifle it was loaded for.