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# Maths question for someone with brains ?

#15
03-21-2008, 01:10 PM
 Platinum Member Join Date: Dec 2001 Location: Mukilteo, WA Posts: 1,092
Yes, as Britz said, you can just divide the dope the computer gives you, in MOA by 1.09 going by those numbers. Or if you have a program that will let you, simply change the click value to match. For example with this one THIS on (listed in the sticky at the top) on the first tab under MOA Value put 1.143 "/100 yds instead of 1.047 and it'll figure your dope correctly. Some programs will let you do that, some won't.

I still recommend doing the yardstick thing (doesn't have to be a yardstick either, just something large measured exactly) because you can get much more accurate results.
#16
03-21-2008, 02:09 PM
 Platinum Member Join Date: Feb 2005 Location: Nevada Posts: 2,782
Down Under Hunter,

+1 to what Jon said.

That number (25) is pretty interesting. If at 100M you move up 20 MOA's and the impact moves 25 inches, then your scope moves the impact point up 1.25" = 1 1/4" at 100 M per MOA. That means that if you have 4 clicks to one MOA, then 1 click at 100M would equal 0.3125". 4x20=80clicks,
80 x 0.3125 = 25" inches.

All this translates to say the in your scope 1 Click = 0.29847 MOAs at 100M. Punching this information and velicity and the conditions, LoadBase says the following:

Note: 20 MOA puts your out to 803M.
16.1 MOA puts you out to 700M. I used a scope height of 2.3".

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Last edited by Eaglet; 03-21-2008 at 05:54 PM.
#17
03-21-2008, 05:05 PM
 Gold Member Join Date: May 2007 Location: VICTORIA AUSTRALIA Posts: 912
Eaglet, Britz and Jon A

Very well explained !

I'll send the scope back for a fix up after I get done with April hunting season.

At least in the meantime I have my drops worked out to 700 and confirmed with the PDA so in the meantime I'll run with that.

This explains my grief of the last few frustrating practice sessions ?

Basically for every 10 moa dialed I would be getting an extra one !

Also my 100 zero was 1 inch high of centre. So there is our difference !

Many thanks again guys. I'm due for better days from now on !

This stuff is a constant learning curve

DUH
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#18
03-21-2008, 05:57 PM
 Silver Member Join Date: Feb 2008 Posts: 121

Quote:
 Originally Posted by Down Under Hunter 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
,,,,,,,,,,,,,,,,,

Peter

Last edited by P KUNDA; 03-21-2008 at 06:03 PM.
#19
03-21-2008, 05:59 PM
 Silver Member Join Date: Feb 2008 Posts: 121

Quote:
 Originally Posted by Down Under Hunter 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
,,,,,,,,,,,

Peter
#20
03-21-2008, 10:10 PM
 Platinum Member Join Date: Feb 2004 Location: Pennsyltucky Posts: 2,630
the real beauty of shooting two groups,one at 100, and another at the same distance after cranking the scope up 20 or 25 MOA, is not only can you tell how far the turrets are moving the point of impact, but you can also see if your scope turrets are tracking on a straight line up and down. this is how i set my croshairs when mounting a scope. keep turning the crosshairs until both groups are perfectly verticle from each other.
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#21
03-21-2008, 11:05 PM
 Gold Member Join Date: May 2007 Location: VICTORIA AUSTRALIA Posts: 912
Dave,

One other little curve ball I forgot to mention. When I shot the rifle for its 100 m zero I did not pay enough close attention to the large black spot on the target. In fact the 100 M zero was 1" high.

Due to time constraints and family demands I have little time to shoot the rifle this week to check this stuff, but after reading your posts I have been running some numbers on exbal. Just trying to see if all the math conclusively proves that the scope clicks are inaccurate and the 1 " high 100 M zero is where it all is going wrong.

I unfortunately dont have the time to play with the gun too much as hunting season starts in one week so I'll run with the numbers below. I wont be shooting past 500 M in this season anyway. Then I will make all corrections needed for the rest of the year.

Facts are these

1. When at 100 lasered meters and dialling 20 moa up I have 25 " of group elevation. ( This is above the 1 " high 100 M group )

2. Scope and mounts are good.

3. Groups are super.

I need the following confirmed ups on a NXS 5-22

200m- 1.25 up

300m- 3.25

400- 5.25

530- 8.5 up

Can anyone tell me what my zero would be being 1 " high at 100 M ?

338 edge (2870 fps estimate) 300 smk .768 bc. 20 ft above sea level BP 30.0, RH 46 % temp 76 f ? 2.1 " above bore. These numbers get me close.

If I can work out my the correct zero, stretch the sight in zero on exbal to this and see where the numbers were at ?

If I was close, I thought I'd do as Jon A suggested and divide my exbal dope with the 1.09 suggested and see if I end up with the correct ups listed above ? Hopefully this will then support the scope clicks being wrong ?

Did that make any sense ?

I know I'm trying to cover too many bases at once, but I'm just trying to satisfy myself I have it nailed down now.

Maybe some of you boys who have more experience with exbal than me can see if I am thinking this through clearly ?

Thanks all for your welcomed assistance. I have more calculations and pieces of paper in front of me than you can imagine !

Happy Easter all !

DUH
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Last edited by Down Under Hunter; 03-22-2008 at 02:52 AM. Reason: spelling

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