by Hoot » Sun Nov 20, 2016 8:07 pm
Just a thought. Are you shooting prone or from a bench? Uphill, downhill, or fairly level? Wind probably not an issue since it happens on different range trips. Possibly some odd barrel harmonic going on. Varmint Al's Web page discusses barrel harmonics, but if you were catching it on the upswing, you would have to dial it out to hit at 50. You can be off a lot in terms of zero at long range and still get a good group at 50 due to the proximity. A test would be to zero at 100 and see how it does when shot at 200, 300, etc.
Grasping at straws for an explanation.
Hoot
In Theory, there is no difference between theory and practice. In Practice, there is.