I FEEL LIKE IM TAKING CRAZY PILLS! 0.8 Mil Vertical Zero Shift Session To Session

[HandgunHTR]

First off, how big are your 5-round groups?

Second, when you are shooting for zero, how many shots are you shooting?

If all you are shooting is 5-round groups, then there is a very good possibility that your zero check groups are actually falling within your cone of impact.

Before you start taking stuff apart, shoot a 20, or better yet a 30-round group to get your true cone of impact and your true zero.

If you did do a 20 or 30 round test to determine your system capability and true zero, and are using that to confirm that you are indeed getting a zero shift, don’t rule out focus and parallax as a potential cause. Most people I know have never taken the time to accurately set up their focus so that the parallax settings are true.

 

[Macintosh]

It’s strange that every time you adjust, when you go back to your other location you are off exactly the amount that you adjusted. If I understand correctly that was consistent multiple times. Makes me think it’s something about the location, not the setup…shot angle not accounted for + Ranges not exactly 100 yards?
0.8mil is a lot though. Hard to think of non-obvious changes that would account for a consistent shift that large.

Can you confirm 0.8mil= center of your 100 yard groups are off from previous zero by roughly 2.75”? How big are your group extreme spreads/how many shots are your zero groups?