Cosine indicator question

Discussion in 'Long Range Hunting & Shooting' started by Bigcat_hunter, Jun 7, 2008.

1. Bigcat_hunterWell-Known Member

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With out a pocket pc which method of calculating cosine is more accurate, multiplying cosine by MOA or sloped yards?

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The same.

3. mattjWell-Known Member

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They actually are not the same -- multiplying the MOA dope by the cosine is the more accurate method of the two.

There's an article on this right here at LRH:

Long Range Hunting - Angle Shooting

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mattj:

Multiplying the cosine to your MOA or Milliradian hold is more accurate than multiplying the cosine to the sloped distance to target.

This is because you are performing your calculation on a pre-calculated angular method of measurement.

5. Brown DogWriters Guild

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Hi Ward,

Hope you are well!

I think the 2nd part of your explanation needs a wee tweak

The reason for your 1st point being spot-on correct is that applying the cos to comeups (or drop) reflects what is going on ballistically, applying it to the slant (laser) range does not.

I'm going to quote myself from a while back:

...and as a common-sense check:

So, to restate myself: The reason for your 1st point being spot-on correct is that applying the cos to comeups (or drop) reflects what is going on ballistically, applying it to the slant (laser) range does not.

All the best

Matt

PS. Thought you might like this pic of a rather technically challenging set of circumstances that faced me earlier this year:

It won't surprise you to learn that we noted a significant vertical wind effect!

Last edited: Jun 8, 2008
6. mattjWell-Known Member

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That's what I said -- or, at least, that's what I was trying to say

7. dmgreeneWell-Known Member

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Brown Dog are you sure this is correct or am I misunderstanding what you are saying? If you shoot at a target that is at a 90 degree angle up or down then theoretically you don't have any drop from the line of sight do you?

David

8. jwp475Well-Known Member

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The only method that is 100% accurate is to run the angle through Exball, IHMO

9. Brown DogWriters Guild

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Please read the six lines following the piece you quoted.....and you will answer your own question .

How tall does the pencil look when held vertically, with your arm vertically above your head?

(worth pointing out that what I'm calling 'drop' is actually the vector resulting from the force/time/acceleration etc of gravity -just easier to illustrate the example by grouping them into 'easy' language -'drop'. Sticking with easy language, for a vertical shot, the drop is straight back down the path of the bullet (in vector terms it will, therefore be a decceleration.)

The only way to reduce the effect of gravity is to get in a space ship

Last edited: Jun 9, 2008
10. Brown DogWriters Guild

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How do you think Exbal is calculating it??!

I'll eat my hat if it isn't applying the cos of the angle to the bullet's drop.

Last edited: Jun 9, 2008
11. dmgreeneWell-Known Member

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BD I guess what I'm trying to say is that most of us (or at least I do) consider drop to be the departure of the bullet flight path from the line of sight. I know that gravity will still affect the bullet no matter what, but the steeper the angle the straighter the bullet path will be. I not saying your wrong, I just didn't understand what you were calling drop.

David

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Angle Cosine Indicator Calculation method and Night Force Ballistic Targeting softwar

Hello Sir (Brown Dog):

We are still around, aren't we? Have wondered what you have been up to and if you have remained in the UK.

Anyway, I just sent in an article that I wrote regarding Night Force Ballistic Targeting software. It should post soon and I think that you will like it.

All my Best,

-Ward

13. kcebcjWell-Known Member

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Great post and really good answers. Information like this is the reason I keep checking this forum. Sure appreciate the people who are in the know for the time you spend answering the complicated questions.

When I was a kid I was taught to pull a little low when shooting up or down hill. I can honestly say that I now know why one does and can figure exactly where to aim.

14. Brown DogWriters Guild

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David,

Sounds as though we're violently agreeing

Ward,

Dropped you a PM.