I remember seeing Ken Oehler's article, but didn't grasp the significance of what he discovered until I read this thread. A friend and mentor of mine had an Oehler Model 43 and he took me along a few times when developing loads. The 43 is one magic box measuring many things including ballistic coefficient for each shot. This was about 15 years ago and you could select G1 or G7 as well as other drag functions when measuring BC.
I remember one test where the measured BCs for 10 shots were all within half a percent of each other, but much higher than expected. Turned out we entered the wrong distance to the target. I bring this up because your statement that "...he and others confuse repeatability with accuracy" rings true in my own experience. I image you've learned that lesson from your own experience.
