I understand what you are trying to do. We all go through the process, sooner or later.
For instance, my brother, Peter, was trying to work up a load for his .36 caliber rifle, with round bottom grooves. He had been trying oversized balls, and patches of .018" but his groups simply were not very good. So, he tried using a smaller diameter ball, and a .012" patch. Groups tightened up right away. He was short of those diameter balls, and the thin patches, so he will be going back out to the range again- probably next week-- to see if he can't get a ball/patch combination that will give him tack driving accuracy that he expects from that barrel.