# center of scope to bore exbal question

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

1. ### lamiglasWell-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. ### geargrinderWell-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. ### SouthpawWell-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. ### morpheus32Member

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Dec 24, 2006
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. ### MomanWell-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. ### kcebcjWell-Known Member

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Jan 28, 2008
For a bolt rifle…….flash hole in the receiver to center scope tube. Use a caliper. Simple to do.

7. ### morpheus32Member

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

8. ### MomanWell-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. ### JRuWell-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. ### lamiglasWell-Known Member

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thanks for the replies guys!