Zeroing for a 20 moa base

merbeau

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Nov 1, 2011
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Hi

I have been shooting in local 600 yd matches and am wanting to start competing at 1,000 yards. To do that I purchased a Nightforce 20 moa base. If I understand this concept, the 20 moa base means the rifle will be 20 inches high at 100 yards. So the rifle has to come down 20 inches to be zeroed at 100 yds which frees up more scope movement upward for longer shots.

Using this formula
Scope Clicks = (amount of desired bullet impact location movement / amount of scope movement per click) x (adjustment distance specified on the scope / distance to the target).
For my scope coming down 20 inches would be 160
clicks. I have 70 clicks per revolution of the scope's elevation turret. So that meas ~ 2.2 revolutions.

Went to the range using the above strategy and fired 10 rounds and never could see where the bullet was hitting. Definitely not on the target.

What am I missing?

Thanks

Robert
 

Barrelnut

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So... sounds like your scope has 1/8" clicks right? If true seems your calculations are about right.
Number one is make sure the rail did not accidently get installed backwards. Please do not ask why I thought of this. LOL.
IMO, when lost and off the paper, it is best to just start over.
I would:
1) Confirm the orientation of the rail.
2) Bore site the scope (whatever method you use)
3) Shoot at a 25 or 50 yard target to get on paper.
The rest will then be easy.
 

ShtrRdy

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I would just start as if you're installing the scope for the first time. Bore sight it and then get a big piece of paper and fire a shot. Adjust from there.
 

KyCarl

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I use a SiteLite SL-500 it will pay for its self in a few years. Every rifle I have used
it on has been on paper at 100 yards!
 

jmcmath

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I like to come in to 50 yards when things aren’t working right. Get it on paper and everything gets simpler. Make sure that base is on right first.
 

merbeau

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Nov 1, 2011
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Thanks to all that replied. The base is on correctly if I interpret the directions correctly. The part of the base (back) that is thicker goes on the rear of the receiver. The Night Force base has RL on the back standing for rear left. So the cant of the base and therefore, the scope is downward from back to front.

BarrelNut, the scope is indeed a 1/8 inch click.

Typically, I place the rifle and scope on my stand, level it and place the stock in a leaf bag holder. I then look through the bore of the rifle and center it on a target using the stand adjustments. I then look through the scope and see where the crosshairs are and adjust.

Sounds as if I should start at 50 yds. Next time at the range I will start there first. Thanks again for the advice.

Cheers,
Robert
 

merbeau

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Nov 1, 2011
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185
Finally had some good weather - well if 30 degrees is good to head back to the range and started at 50 yards as most suggested. The rifle was shooting high and since I attach my targets to the top of the backboard the rounds were going over target. I then went back to 100 yards, placed three poster boards with two side-by-side vertically and extended a foot above the backboard with the third horizontal on the bottom to the two vertical. I cranked the elevation knob almost near the bottom and placed a target in the middle and fired. Success!! Was able to zero the scope. Reading about the concept is one thing, seeing it for real is another. I now have the full elevation available for long range shooting. Many thanks to all that replied.

Robert
 

jimisbell

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ingleside, TX
Thanks for asking the question. I have a 20 MOA mount on the way and will be doing the same thing in a week.
 

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