So if we think about it, the speed of the bullet less important than the speed of the vibrations. Point two of a grain of powder extra, won't change bullet speed much, but it has a big impact on vibration speed as do small tuner movements.
The above quote is exact reasoning why i dont take any notice to muzzle velocity..
When I looked at your diagrams of groups above, I was very surprised what effect the tuner had made to those groups, more so now knowing how small the adjustments were...
There is no way at 140y
with a naked barrel I would get "coning" characteristics like that... If i was to do .2 increments over 6 loads/tests working up to my accuracy load not one of those groups would measure over .250"...(3 shots) Regardless of barrel profile...
My thoughts were when I seen them....WOW and ive now got to ask...
Was the load used in those diagrams the most accurate tested load before tuner adjustments?
Are those "coning" characteristics normal when using a tuner?
Was those "coning" characteristics apparent before tuner was adjusted when working up a load?
This is only an assumption from diagrams but is it possible there is a fitting error or is it possible tuner has a balance issue? (heavier one side)..
Just my thoughts