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1425 yard whitetail
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<blockquote data-quote="trebark" data-source="post: 572237" data-attributes="member: 19172"><p>Thanks for the additional info. Always glad to know I'm not alone in the slight anxiety caused when attempting a long shot. Here's some info I can offer, maybe it will help the next time you're ready to make another long shot....</p><p> </p><p>For making a long shot like the one you took, once you have taken into consideration the atmospheric condition (temp, barometric pressure, altitude) there are five factors to consider. They are:</p><p> </p><p><strong>Elevation</strong> - ballistic program will provide this data.</p><p><strong>Windage</strong> - ballistic program will also tell you how much windage compensation is required.</p><p><strong>Coriolis</strong> - while I understand coriolis, I have never quite developed a formula for calculating it.</p><p><strong>Spin Drift</strong> - with a right-twist barrel, it will cause your point of impact to move to the right. many ballistic programs can calculate spin drift.</p><p><strong>Magnus Effect</strong> - <a href="http://en.wikipedia.org/wiki/Magnus_effect" target="_blank">http://en.wikipedia.org/wiki/Magnus_effect</a> when the bullet is spinning threw the air (assuming a right-twist), the air pressure on the right side of the bullet is lower than the left. As a result, with a 9 o'clock wind, the bullet will move down and to the right. With a 3 o'clock wind, it will move the bullet up and to the left. The correction for magnus effect is 15% of your spin drift + windage compensation. So for instance, with your 1425yard shot, you probably needed 1.5moa left windage to correct for spin drift and 9moa left wind for a 12mph 9 o'clock wind (~.75moa per mph) for a total 10.5moa left windage. As a result, you would need an additional 1.575moa additional 'up' (10.5 x .15=1.575).</p><p> </p><p>If the wind were blowing in the opposite direction, You would still need 1.5moa 'left' for spin drift, and 9moa 'right' for wind for a total 7.5moa 'right'. As a result, 1.125moa 'down' to compensate for magnus effect (7.5 x .15 = 1.125)</p><p> </p><p>Also, this caclulation assumes no up or down angle.</p></blockquote><p></p>
[QUOTE="trebark, post: 572237, member: 19172"] Thanks for the additional info. Always glad to know I'm not alone in the slight anxiety caused when attempting a long shot. Here's some info I can offer, maybe it will help the next time you're ready to make another long shot.... For making a long shot like the one you took, once you have taken into consideration the atmospheric condition (temp, barometric pressure, altitude) there are five factors to consider. They are: [B]Elevation[/B] - ballistic program will provide this data. [B]Windage[/B] - ballistic program will also tell you how much windage compensation is required. [B]Coriolis[/B] - while I understand coriolis, I have never quite developed a formula for calculating it. [B]Spin Drift[/B] - with a right-twist barrel, it will cause your point of impact to move to the right. many ballistic programs can calculate spin drift. [B]Magnus Effect[/B] - [URL]http://en.wikipedia.org/wiki/Magnus_effect[/URL] when the bullet is spinning threw the air (assuming a right-twist), the air pressure on the right side of the bullet is lower than the left. As a result, with a 9 o'clock wind, the bullet will move down and to the right. With a 3 o'clock wind, it will move the bullet up and to the left. The correction for magnus effect is 15% of your spin drift + windage compensation. So for instance, with your 1425yard shot, you probably needed 1.5moa left windage to correct for spin drift and 9moa left wind for a 12mph 9 o'clock wind (~.75moa per mph) for a total 10.5moa left windage. As a result, you would need an additional 1.575moa additional 'up' (10.5 x .15=1.575). If the wind were blowing in the opposite direction, You would still need 1.5moa 'left' for spin drift, and 9moa 'right' for wind for a total 7.5moa 'right'. As a result, 1.125moa 'down' to compensate for magnus effect (7.5 x .15 = 1.125) Also, this caclulation assumes no up or down angle. [/QUOTE]
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