Scope height and Ballistic Programs

Discussion in 'General Discussion' started by kbillet, Dec 27, 2013.

  1. kbillet

    kbillet Member

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    If your scope is mounted on a 20 MOA rail, from where do you take your height measurement for a ballistic program?
     
  2. Toptuna

    Toptuna Well-Known Member

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    I had the same question. Never got a good answer.gun)
     
  3. kcebcj

    kcebcj Well-Known Member

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    Right or wrong have always measure right at the turrets...center of bolt to center of tube. The turrets are usually about the center of the rail. Get's it close enough for me. I use a pair of dividers then just measure.
     
  4. varmintH8R

    varmintH8R Well-Known Member

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    This is what I do as well.

    For fun, I added a quarter inch to the scope height field in Bullet Flight. It changes the dope just a shade over 3"..........at 3000 yds.

    I would say get as close as possible and confirm your drops, and the vertical cant from your 20MOA rail should be a non-factor.
     
  5. Bullet bumper

    Bullet bumper Well-Known Member

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    The best method to measure scope height is to measure bolt diameter.
    Measure scope tube diameter .
    Measure distance between top of bolt and base of tube .
    Take half the tube diameter and half the bolt diameter and add them together.
    Then add the product to the distance between the bolt top and tube base .

    The slight difference between a parallel mount and a 20 Moa mount would be hard to see in a calculated ballistic trajectory .
    A 20 MOA rail 6 inch long is only .035 higher at the rear than the front . The actual scope height difference would only be half that if one scope height is taken near the turrets .
    I am not sure it makes any difference as the line of sight is always at an angle to the barrel .
     
  6. kbillet

    kbillet Member

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    Thanks Guys. I'll go with the measurements at the turret.