# Maths question for someone with brains ?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Down Under Hunter, Mar 20, 2008.

1. ### Down Under HunterWell-Known Member

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Happy Easter all !

The question is this-

I have my rifle zeroed at 100 meters.

If I dial 20 moa up, how many inches should the group move up at 100 M ?

My brain is hurting trying to work this out !

Remember to convert the yards to meters.

Cheers

DUH

2. ### jwp475Well-Known Member

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I believe that it will move it 23 inches....

Last edited: Mar 20, 2008

3. ### Willys46Well-Known Member

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Check my math

1.047 / 100= .01047 That is how many MOA per yard
100 meters= 109.36133 yards
so there is .01047*109.36133=1.145 moa Per 100 meters

20 moa * 1.145= 22.9 inches

That is my guess! it seems close in my book but who knows.

Willys

4. ### britzWell-Known Member

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I'm comming out with 22.91"

Using the conversion numbers of 109.4 yards per 100 meters and 1.047"= 1MOA

5. ### britzWell-Known Member

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Took me too long, LOL

6. ### Willys46Well-Known Member

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looks close

Come on guys--didn't your math teacher tell you you do not get credit enless you show your work! How can we see how you figured it out!

Looks like we all got some what close.
We must all be really smartlight bulb

7. ### britzWell-Known Member

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I was in too much of a hurry to show it after I did it on paper -> but I lost the race anyway lol. Besides, History is my specialty not math (got sick of the theroms, postulets, and other things )

8. ### jwp475Well-Known Member

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Take 1.0472 inches which is 1 MOA at 100 yards and divde it by 100 and then multiply the answer by the yards in 100 meters and then multiply by 20 and that is your answer..

9. ### Down Under HunterWell-Known Member

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Thanks fellas !

I knew I'd get a bite if I cast that one out there !

Many thanks again !

DUH

10. ### EagletWell-Known Member

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1 MOA = 0.01'00" = 0.0166667° ----- 100M(Tan(0.0166667°)) = 0.0290888M @100M.
So, 1 MOA = 29.088822 mm. 1 inch = 25.4 mm
Therefore 1 MOA = 1.145229" @ 100 METERS
20 MOA's equals 22.90 inches.​

This way is more complicated but Willy's46 gave me no choice. He'd already done it the way I would have. Lot of fun!

Last edited: Mar 21, 2008
11. ### Down Under HunterWell-Known Member

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O.K.

This will test you all,

If I dialled 20 moa, and infact shifted the group 25 " in elevation, how many moa will I be out if I ran these numbers at 700 M

338 edge
300 smk
velocity 2830

alt 200 ft
temp 80 degrees
rh 46 %
bp 30.0

Just have a feeling that incorrect click adjustments may be throwing my elevation out ?

Hope the question gives you everything you need to answer it.

Thanks guys

DUH

12. ### Jon AWell-Known Member

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You need to nail down the click value on your scope, while eliminating other variables (is it securely mounted now? Are you sure it's holding zero?) or you may be chasing your tail for a long time.

Try a yardstick test at 100. Put the stick vertically on the target. With the rifle very securely held, put your crosshairs on the very top of it and have somebody else crank the turret while you watch the reticle. Ensure it moves smoothly and that each click seems to move the same amount without getting hung up or jumping at all. See how many clicks it takes to get to the bottom of the stick. Do it a few times until you're sure of the answer.

That will tell you what your scope is doing without including possible errors created by shooter, rifle or mounts.

13. ### Down Under HunterWell-Known Member

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912
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Jon,

There is no problem now with the mounts. All rock solid.

Basically if the previous posts are accurate, for 20 moa dialed on my scope I should get 22.9" up instead of the 25 I accually get " ? That itself will cause grief.

The rifle simply tack holes groups like I have never seen, but I struggle for good first round elevation dope.

I gave the 700 M example because I routinely practice on a steel gong at that range, and I would like to know what elevation moa others get when they run the previous mentioned numbers through their PDA. I can then compare that to my adjusted drop chart. If they match I feel I have found the missing piece of the puzzle.

So basically I'd like to work out the moa diffence at 700m with the 2 " difference from the 20 moa dialed ? Did that make eany sense ? I think from memory you should get around 16.75 up. Would the difference in click adjustments result in a corrected dope of between 13-14 moa for the 700 M distance