Thanks Dthomas3523. That makes sense to me and I agree with you. I was aiming at the Center of the Red Dot on the target. My Gun was level. I was shooting off rests fore and aft. (Pics below on string on upgrading my Rest from Model 1200 to Model 2400.) I normally am pretty sensitive to my reticle being square with the world. I do realize that my approach of using the reticle requires a Vertical Center Reticle. The Center of the Group is just under 2" from the center of the Red Circle Bull's Eye. I appreciate your thoughts. 4CertainSpindrift could be part of it. Most of the times I've seen this happen is that people's scopes were canted oh so very slightly. If you were aiming center in the above picture, spindrift would not be that much at 150y.
There are pics of my rig on the string below: https://www.snipershide.com/shootin...etshooting-com-m-1200-rest-to-m-2400.7025330/