Vertical stringing cause?

[browningautorifle]

Lastly...shooter inconsistency.

You didn't tell us whether you're shooting off a sandbag or your elbows. If you want to accurately group, take away as much of the human factor as you can. I shoot off sandbags now because I ain't gettin' younger and steadier. When we coached in the army, vertical groups were breathing. A diagonal group was a change in position like elbow shift. Bag it and try again.