new scope doesnt line up with action

Discussion in 'Long Range Scopes and Other Optics' started by upacreek, Oct 7, 2013.

  1. upacreek

    upacreek Well-Known Member

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    I mounted a vortex scope to my rifle. Centered up the windage. Bore sighted. Adjusted the Leopold rear mount screws to center windage. Afterwards I noticed the rear ring is about 1/8" left of center to the base. I spent half an hour counting clicks on the scope to verify scope was centered. When I shotit the rear ring needed moved over another turn more. I think the scope is screwed up. Is there some way the aadjustment cap is limiting adjustment? Should I send the scope in?
     
  2. MudRunner2005

    MudRunner2005 Well-Known Member

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    Why not center the scope up first, then adjust your crosshairs for bore-sighting, and reset your turrets to 0... lightbulb

    :cool:
     

  3. upacreek

    upacreek Well-Known Member

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    I could......but there would be almost no adjustment on one side and a ton on the other. I guess the question is this normal?
     
  4. bruce_ventura

    bruce_ventura Well-Known Member

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    You're assuming that the mechanical zero is the same as the optical zero, and it may not be.

    You found the mechanical zero by counting clicks from one limit to the other, and then setting the turret to half that value.

    The optical zero can be found on a mounted scope by 1) placing a small mirror flat against the objective, 2) looking through the eyepiece, 3) rotating the turrets until the reticle and its reflected image lie on top of each other. I helps to let a little light creep into the objective (cover the objective only about 95% with the mirror). This process takes a little practice to do well.

    If the reticle and the reflection are both visible, then instead of dialing the turret you can measure the angular separation between them using the reticle. Then divide that measured value by 2 to get the angular offset from optical zero. This way you don't have to rotate the turrets away from the zero you just established.

    If the rings were separated by 4", then 1/8" of adjustment would correspond to 107 MOA of windage. I doubt that your Vortex scope has enough true windage adjustment to account for all the windage offset that you've dialed in on the base. It sounds to me like your barrel is not installed straight. Is this a production rifle? If so what model?
     
  5. upacreek

    upacreek Well-Known Member

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    This is a Winchester m70. Factory barrel.
     
  6. cowboy

    cowboy Well-Known Member

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    Are your holes for the bases tapped square on your action? Having holes tapped offset is not an uncommon problem on some actions. There is a couple of solutions if your holes are not tapped sguare with your bore but it can become frustrsating.

    I would bet it is not a scope problem. Switch scopes out if you can and if your having the same problem you more than likely need to look elsewhere for the problem. I have seen offset holes more than once but usually on the 700 rem actions.
     
  7. Gary Kaney

    Gary Kaney Well-Known Member

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    I had the same thing with a Mod. 70 Coyote Lite ( circa 2005 tje year they closed the New Haven plant) Those holes were so far off center you could see it. Then the spacing was for a WSSM.
     
    Last edited: Oct 8, 2013
  8. bruce_ventura

    bruce_ventura Well-Known Member

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    I don't disagree with Cowboy and Gary. The problem could be base misalignment, barrel misalignment, and/or scope mechanical zero offest. The alignment error is so large, though, that a combination of two or more factors seems likely.

    I suggest you use a couple of straight edges to check base/receiver alignment. Then use a straight edge to check barrel/receiver alignment. Then check for a mechanical zero offset, as discussed above.

    Let us know what you find out.
     
  9. upacreek

    upacreek Well-Known Member

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    I have been playing around with bullet seat depth. Got it to .60-.85" mos pretty consistently. I am gonna hunt with it and then check everything out in November. Just a visual check looks like bases are centered. I suspect the scope. I will check it with a mirror as described earlier. I will post results when I figure it out.