Ive been thinking about your testing, and I was wondering what your comparing against.. As your results maybe conflicting against one scope to another...
"Immediately after the first shot complete disagreement between 3 scopes"
I may be wrong and not exactly understand your testing but without a fixed scope (neutral) how can you get accurate results..
One way too check a rifle scope for repeatability is put a collimator on the end of your barrel and adjust your focus and rear parallax, scopes that are shifting point of impact will shift with this test...
I have a platform that will take up to 4 scopes side by side. This time I only used 3 scopes, because from past experience with my scopes, I hadn't seen any disagreement of more than 0.15 MOA. What I need to have is at least two scopes that agree very well, and that will make any others that don't agree suspect. After the first shot no two scopes agreed, so only one (or none) stayed put, and I had no way of knowing which one. For my next test I'll use 4 scopes, and won't include the Sightron, because it seems to have a problem. With 4 scopes there is a better chance of at least two of them agreeing. The "frozen" scope used in the US tests makes things simpler, but would you be 100% sure that it doesn't move? Also it means wrecking a scope. I actually bought the Weaver T24 purposely for the tester, because they have a reputation for reliable mechanicals, but at least it can be used for other things.
The aim of this testing is to see if the POA moves between shots because of recoil. The collimator would detect changes because of focus, power etc. adjustments, but I think the grid idea works better in this case.