I hadn't seen any testing before that was this good. It does seem to confirm a tuners effect. If you study the groups you can even see the vertical that went away as group size decreased. Before the tuner was added he said the gun was grouping at .253" at 50 yards. When the tuner was added it appears groups increased somewhat but it's not clear exactly how much - it could have been as much as 100%. After tuning to one of the best sweet spots groups dropped to about .134" (converted to 50 yards). So I would call the improvement a reduction in group size of .115" at 50 yards. This is much larger than the improvement I said you should get. Shows you how wrong I was, and the value of having some numbers.
My estimate was based on having a velocity spread of 40 fps. His spread was probably less than this but I'm not claiming this is why I was so much in error. For the moment I'm just going to have to say: y'all was right and I was wrong! I think everybody has to admit now, MKnarr has one super gun - I've never seen a rimfire average .134" groups at 50 yards.