Alex, I'm totally with you. The bullets and targets never lie. Reading what you've posted on here over the years has been extremely helpful to me psonally. Frankly, a lot of what I do comes directly from stuff you've written. Not to get soft or anything but I want you to know that I appreciate you sharing your experience and knowledge.
The next thing I think I'm going to test is sorting brass by velocity. Meaning I'm going to load up 20 rounds, shoot them over the chrony, and then cull the cases that aren't within 5fps of each other. Then re-prep, load, and shoot the keepers over the chrony again and see if just doing that will result in lower ES/SD. Have you tried that?