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Cosine Indicator

 
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  #22  
Old 11-21-2003, 10:27 AM
 
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Re: Cosine Indicator

Here is a link that you might be interested in reviewing. Snipers Hide Forum - Angle Cosine Indicator
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  #23  
Old 11-21-2003, 04:09 PM
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Join Date: Jun 2001
Location: Palmer, Alaska
Posts: 2,539
Re: Cosine Indicator

After reading throught the topic, which I missed, as I don't post there all that often, I can't hardly believe the resolution isn't 1 degree with the ACI. It is an analog device that can easily be broken down visually with no trouble at all. I can easily break down the .001" marks on my dial caliper to .0002" increments, and my 2 MOA tics on the R2 reticle the same way. How in the hell would anyone use a mildot reticle without this practice also. [img]images/icons/rolleyes.gif[/img]

I wonder if the guys using ATrag1p on the Handspring Visor were doing the manual cosine calcs, or just entering the angle into the "Angle" function on the ATrag program.

I'm guessing that the drum that the cosine numbers are printed on is all that is needed for the left hand version?

Is the drum not symetrical and the ACI cannot be disassembled and the the drum reversed to use on a lefty? Or can it be reversed? My dad shoots lefty.
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Brent Moffitt
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  #24  
Old 11-21-2003, 05:51 PM
 
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Re: Cosine Indicator

The wheel can be reversed, however it is better to utilize a wheel that is made for a lefty because of the interior design. If I have advance notice, I can manufacture "special order", a left handed version.
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  #25  
Old 12-06-2004, 05:52 PM
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Join Date: Jul 2003
Posts: 32
Re: Cosine Indicator

Brent,

I have seen the same discrepancies between ballistic calculators and the results from using the Cosine multiplier.

Wish I knew why they're so far off. You wouldn't think that all those professional snipers were wrong in their praise of the ACI?

BC
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  #26  
Old 12-06-2004, 09:16 PM
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Join Date: Oct 2003
Location: Randolph
Posts: 57
Re: Cosine Indicator

I'm definately no expert on the subject and haven't done much angle shooting in the real world but I have read quite a bit about the subject. I've read the difference between the angle cosine difference and some ballistics software is that the software takes into account for the time of flight. If you figure out your angle and take the cosine of it; that'll give you the distance that gravity has and effect on the bullet (ie. the horizontal distance). This does not however take into account that the bullet is still traveling the ranged distance to the target (actual distance). I know Exbal and the Sierra software take these factors into account. I would think a combination of the ACI to get your angle and then using the angle chart to get the scope adjustment would be the correct way. But like I said, I have no real world experience in this. Interested in your findings; keep us posted.

[ 12-06-2004: Message edited by: Cobber ]
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  #27  
Old 12-06-2004, 09:52 PM
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Join Date: Jul 2003
Posts: 32
Re: Cosine Indicator

Interesting. That makes some sense, but it assumes that the flight time would be the same.

Wouldn't the bullet get there sooner when flying at an angle to the target for the same reason the yardage is shortened, i.e. less gravity effect?

TBC

I'm definately no expert on the subject and haven't done much angle shooting in the real world but I have read quite a bit about the subject. I've read the difference between the angle cosine difference and some ballistics software is that the software takes into account for the time of flight. If you figure out your angle and take the cosine of it; that'll give you the distance that gravity has and effect on the bullet (ie. the horizontal distance). This does not however take into account that the bullet is still traveling the ranged distance to the target (actual distance). I know Exbal and the Sierra software take these factors into account. I would think a combination of the ACI to get your angle and then using the angle chart to get the scope adjustment would be the correct way. But like I said, I have no real world experience in this. Interested in your findings; keep us posted.
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  #28  
Old 12-06-2004, 10:27 PM
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Join Date: Jul 2003
Posts: 32
Re: Cosine Indicator

Oh and BTW ...

A Leupold Rifleman scope ring works good for mounting a ACI. They are sectioned vertically.



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