I'm working on a 7mm STW load for 180gr VLD Bergers and am trying to sort to eliminate as much variation as possible. I've sorted by weight, and right now I'm sorting again by the length of the bearing surface. What other dimesions should I consider measuring? Total length? Base to ogive? Nose to ogive? Or other? A person could go crazy sorting out all the possible variables. By the way the range I'm getting is .12mm total variation on the bearing surface, and .4gr total variation on the bullet weights. Does this sound excessive, normal or good?