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Updraft question ?

 
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  #1  
Old 09-15-2008, 06:28 AM
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Updraft question ?

Say you are faced with a 750 yard shot into a dead head wind. Closest two thirds of the shot are downhill 20 degree slope then up to the target appox .99 cos. 338 edge. wind speed is about 4 mph hitting you on the nose.

How much would you knock off for elevation if faced with the situation ?

DUH
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  #2  
Old 09-15-2008, 07:19 AM
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Re: Updraft question ?

With the provided information, I am guessing about 2.90 MOA off elevation dial up.

Last edited by trueblue; 09-15-2008 at 07:24 AM.
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  #3  
Old 09-15-2008, 10:33 AM
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Re: Updraft question ?

I'd shoot it dialed for 700 yards...
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  #4  
Old 09-15-2008, 10:54 AM
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Re: Updraft question ?

trueblue,
Not trying to be a smartallec but where did you come up with that? A 4mph full value wind will only deviate a 300gr SMk (@ 2800fps) 1.5moa off course at 742.5 yards (750 X .99). A 20degree angled up wind would translate into a 1/4 value so that turns the 4 mph wind into a 1 mph wind. A 1mph wind will deviate the 300gr bullet .25moa @ 742 yards, and that is if the wind hits it over the entire range. The updraft the bullet will encounter will only be momentarily when the bullet leaves the muzzle and then it'll be hit with a 4mph zero value head wind. The only elevation change I would make is for the .25moa correction for distance to target(742 not 750). But then again the picture I get from the scenerio is you would be shooting from one hillside/top to another. If that's the case I would be looking for signs of a cross wind in the valley.
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Old 09-15-2008, 10:59 AM
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Re: Updraft question ?

So it's not a downhill shot... it's a cross canyon shot at a target that's at nearly equal elevation?? Frickin' story problems... never could figure them out.
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  #6  
Old 09-15-2008, 11:37 AM
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Re: Updraft question ?

Quote:
Originally Posted by yote bomber View Post
So it's not a downhill shot... it's a cross canyon shot at a target that's at nearly equal elevation?? Frickin' story problems... never could figure them out.
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  #7  
Old 09-15-2008, 02:05 PM
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Re: Updraft question ?

Bravo,

Posted that before my coffee this morning, and worked off dial up and not wind. My revised # is take .60 MOA off dial up. If I am understanding the scenario, you have 500 yards with a 4mph updraft, so at 500 yards w/10mph wind is 1.5 MOA @ 2800 FPS. 1.5 x .4(4mph wind)= .60 MOA.
Take that amount off your dial up.
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