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Angle Cosine Indicator ~ Confusion

 
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  #1  
Old 09-12-2011, 03:44 PM
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Angle Cosine Indicator ~ Confusion

At the great risk of embarrassing myself, not the first time, I have a question.

So I have the Angle Cosine Indicator ready to bolt on my rig.

I am out in the field and get my cosine reading, say 91.

I range my target at 500 yards.

I simply multiply 500 x .91 which gives me 455 yards.
Correct?

Thanks!
PD
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  #2  
Old 09-12-2011, 04:10 PM
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Join Date: Feb 2011
Location: Halfway between Lubbock and Dallas
Posts: 4,857
Re: Angle Cosine Indicator ~ Confusion

Quote:
Originally Posted by Propdoc03 View Post
At the great risk of embarrassing myself, not the first time, I have a question.

So I have the Angle Cosine Indicator ready to bolt on my rig.

I am out in the field and get my cosine reading, say 91.

I range my target at 500 yards.

I simply multiply 500 x .91 which gives me 455 yards.
Correct?

Thanks!
PD
Pretty much. There's a good in depth article explaining the how comes, why for's etc here.

Angle Shooting
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  #3  
Old 09-12-2011, 07:05 PM
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Join Date: Dec 2006
Posts: 61
Re: Angle Cosine Indicator ~ Knights Armament BulletFlight app

Very good, thanks WildRose!

For some reason I was trying to make this more difficult or something. I was thinking I need the angle to put into my Knights Armament BulletFlight app.
I had read up on everything but for some reason it just wasnt clicking.
I may not be fast but I am slow ;-)

Now I just range the big muley below, get my cosine reading, calc it, enter my atmospheric conditions, dial it, pray again, drop it! :-)



Cheers
PD

Last edited by Propdoc03; 09-12-2011 at 08:57 PM.
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  #4  
Old 09-12-2011, 11:23 PM
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Location: Pennsylvania
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Re: Angle Cosine Indicator ~ Confusion

I believe you also can take your cosign and multiply it by your MOA and this will give you your adjustment!

ex..

500 yards = 9 MOA
20 degree angle = .94 cosign
.94 cosign x 9 MOA = 8.46 MOA or call it 8.5 MOA
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  #5  
Old 09-12-2011, 11:50 PM
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Re: Angle Cosine Indicator ~ Confusion

imputing your angel into a ballistics program will give you the best solution. apllying your cosign number to your come-ups will be the next best. your yardage will be the least accurate of the three methods.
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  #6  
Old 09-12-2011, 11:54 PM
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Join Date: Feb 2011
Location: Halfway between Lubbock and Dallas
Posts: 4,857
Re: Angle Cosine Indicator ~ Knights Armament BulletFlight app

Quote:
Originally Posted by Propdoc03 View Post
Very good, thanks WildRose!

For some reason I was trying to make this more difficult or something. I was thinking I need the angle to put into my Knights Armament BulletFlight app.
I had read up on everything but for some reason it just wasnt clicking.
I may not be fast but I am slow ;-)

Now I just range the big muley below, get my cosine reading, calc it, enter my atmospheric conditions, dial it, pray again, drop it! :-)



Cheers
PD
I learned to follow this axiom years ago. KISS

Keep

It

Simple

Stupid.

No need to over complicate it. If you are using a ballistic computer in the field, then just input either the angle or the angle cosine as your program calls for it along with the other data.

Some of us dinosaurs are still stuck on pencil and paper or doing the math in our heads as we go though HA!
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  #7  
Old 09-13-2011, 04:07 AM
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Join Date: Oct 2010
Posts: 72
Re: Angle Cosine Indicator ~ Confusion

Quote:
Originally Posted by C.O. Shooter View Post
I believe you also can take your cosign and multiply it by your MOA and this will give you your adjustment!

ex..

500 yards = 9 MOA
20 degree angle = .94 cosign
.94 cosign x 9 MOA = 8.46 MOA or call it 8.5 MOA
I don't believe that this will give near the same result as multiplying the cosine by the yardage since the yardage is a linear function and the moa drop is a geometric function, I may be wrong, but I believe if you try to work the problem the two different ways you will get two different results. Only one of the methods can be correct if they give two different answers.

For example for my 6.5-284 the moa drop at 1000 yds is about 26 moa. 26 x .94 = 24.44. If I multiply 1000 x .94 I get 940 yds which shows up as about 23 moa on my ballistic chart. The results in a 14.4 inch differerence in POI and I will miss that antelope. The divergence gets even worse as you increase the angle.

The correct method is to multiply the yardage by the cosine for corrected yardage and use that yardage to get the moa drop from your chart or program. Of course some programs have a provision to enter the angle or cosine. Ballistic FTE on my iPhone does the whole thing for me automatically since the iphome has the capabilitie to measue angles from level and I have a bracket to mount it to my gun.
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