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Zero Shift - One Month of Tracking


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  • Zero Shift - One Month of Tracking

    Over the past month, I've been tracking the POI of my first groups of the day/session (cold bore + 2 or more rounds). After I shoot my first group, I put in a correction and carry on with my practice / match. So far I've got ~2.5 moa of left shift built up over a month. My vertical varies quite a bit, but whatever adjustment I put in, I end up taking it out sometime later.
    Date Time Vertical Horizontal Location Notes
    10/30/2017 AM -0.5 -0.25 Rifle's Only
    10/30/2017 PM -1.25 -0.25 Rifle's Only
    11/1/2017 AM 1 -0.25 Rifle's Only
    11/2/2017 AM -0.5 0 Rifle's Only
    11/3/2017 AM 0.5 0 Rifle's Only
    11/18/2017 PM 0.25 -0.25 Santa Clara Tightened mount cross-bolts
    11/24/2017 AM 0.25 -0.5 Pala
    11/26/2017 AM 1 -0.5 Pala
    11/26/2017 AM -1 -0.5 Pala
    Overall Shift -0.25 -2.5
    Anyone else tracking their Zeros? Does this type of shifting zero look pretty common?

    Today, mid-match, my zero shifted 1 moa low - out of nowhere I started missing low at distance then confirmed on paper, is this normal too?

    I'm running an atacr 5-25 F1 in a Spuhr on a pinned rail. I'm pretty confident its more FoM related than equipment.

  • #2
    A good zero is something Iím picky about , one less error to
    account for at long range . The four rifles I have with March
    scopes show no zero shift whatsoever other than encironmental
    shift . To clarify , the 100 target I use for this at local range requires
    shooting over a 50 berm that is quite high . Winds are switchy there ,
    so you can shoot a quick group in one wind condition , and shoot
    another group 5 minutes later and see it print in a different spot around
    the X .

    No no issues with the Hensoldt or Schmidt either : only problem
    child I have is a PST on a 223 trainer that insists on swapping zero
    from up to 0.3 Mil left or right , seemingly at random . Itís going back
    to be replaced soon , hopefully the local Aus distributor has run out
    of Gen 1 units and Iíll get a Gen 2 replacement .


    • #3
      Tag for info on this....

      Had this same problem 2 years ago. Narrowed it down to the crappy pipe foam/duct tape cheek riser and incorrect NPA. Went away with a stock pack. Either that or my technique just evolved.


      • #4
        Admittedly I've never tracked my zero before, but that seems like a lot of shifting. I almost never have to adjust by more than a tenth of a mil, and usually it is spot on.

        WB300 might be on to something. Are all these zeros taken from the same position? Or are some from prone, some from bench, etc? Your position behind the rifle and the pressure you apply will affect your zero.


        • #5
          There is a group bias being formed that looks more like shooting position (head on stock/cheekweld) or trigger control than scope issues.

          As kthomas as - what is your standard position? And is your scope set up correctly - when you chose your eyes and relax is the article in the same position when you open them?


          • #6
            I think if all of us are honest we gets slight shifts as a common event. I can go for months with the same zero then there it is, a shift. Sometimes it'll go back the next time out and sometimes not. If you think about it there are a lot of factors going on that influence us and the rifle system. For instance when I shoot in soft cinders then go to concrete the zero goes a click high. When I go to an out of town match there is often a rezero needed, like a click here and there.


            • #7
              Thanks all for the insights.

              I'm going to test a few variations of my hold - shoulder pocket placement, cheek pressure, grip pressure, to see what that does to my zero, and if I can replicate the vertical shifts that way. I also want to see what a less than perfect parallax setting does to my zero.