center of scope to bore exbal question

Discussion in 'Long Range Hunting & Shooting' started by lamiglas, Apr 29, 2010.

  1. lamiglas

    lamiglas Well-Known Member

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    What i am doing now seems to work, but a friend and I are doing this a little different so i wanted to hear how you all are doing this. do you measure the distance from center of bore to center of scope to input into exbal from:

    1) near the bolt, or

    2) at the front of the scope


    with a slanted base the two measurements would be slightly different ( i am thinking) but please correct if wrong.


    thanks alot guys.
     
  2. geargrinder

    geargrinder Well-Known Member

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    I measure the distance between the bottom of the scope and the top of the bolt. Then I add half the diameter of the scope tube and half the diameter of the bolt.
     

  3. Southpaw

    Southpaw Well-Known Member

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    What I was always told, and what I do is use the middle of the bolt. I measure just in front or behind the turrets, which ever is closest.

    Works for me.

    Southpaw
     
  4. morpheus32

    morpheus32 Member

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    I take a slightly different approach when looking at the height of the scope above the barrel.

    From the objective end, I measure the scope complete. I then measure the gap between the bottom of the scope and the top of the barrel. I thing measure the barrel just below the objective end. Add all three and divide by two. It works well for me and is vary accurate as I can use my calipers to measure each. I would suggest this method takes out some of the guessing on the centre.
     
  5. Moman

    Moman Well-Known Member

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    I can see dividing the objective diameter and the barrel by two, but why don't you leave the distance between barrel and scope whole?
     
  6. kcebcj

    kcebcj Well-Known Member

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    For a bolt rifle…….flash hole in the receiver to center scope tube. Use a caliper. Simple to do.
     
  7. morpheus32

    morpheus32 Member

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    My bad...that is what I meant....
     
  8. Moman

    Moman Well-Known Member

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    I figured that's what you meant. I basically do the same thing. I measure with calibers right at the objective but have been wondering how accurate this is with a MOA base. I think it would be good with a standard base but not sure about the MOA. Got to give it some more thought.
     
  9. JRu

    JRu Well-Known Member

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    20 MOA would be one third of a degree. Over the horizontal distance of 15" that makes for a vertical difference of less than .1" . So it doesn't really matter much.

    If you measure from the front of the scope, just remember to add .05" and you're GTG, that's how little of a difference it makes :)
     
  10. lamiglas

    lamiglas Well-Known Member

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    thanks for the replies guys!