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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Wind Drift; First Third vs. Last Third of Target Range
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<blockquote data-quote="Bart B" data-source="post: 1125202" data-attributes="member: 5302"><p>Here's another interesting thing about wind. The higher a bullet is above the line of sight, the greater the cross wind speeds will be. Consider this table I built using the formulas that helps people installing wind turbines for generating electricity:</p><p></p><p><img src="http://i735.photobucket.com/albums/ww351/BartBob/eb601d71-8248-4d41-8ff6-384596b75328.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>A .308 Win bullet will have a maximum ordinate of about 3 feet above the line of sight on its way to a 600 yard target. Same cartridge zeroed at 1000 yards, it's bullet goes about 11 feet above the line of sight to the target. For a .300 Win Mag, the maximum ordinates are about 2/3rds as much. Both maximum ordinates are about 55% of the zero range.</p><p></p><p>If the cross wind's 15 mph fifteen feet above the line of sight across all the terrain types shown across their columns, the actual wind speed in the line of sight is shown in bold text.</p><p></p><p>All of this is why the first 20 or so firing points at the west side of the 1000-yard range at Camp Perry were eventually not used. The tree line on the west side was so close to the first 20 or so shooters, they had a wind advantage of getting less cross winds from the west that those at the east side of the firing line some 70 firing points further from the tree line.</p><p></p><p>As far as I know, none of this is used in software calculating wind drift for bullets. It all assumes the same crosswind speed for all bullet heights above the line of sight. </p><p></p><p>I can imagine what the cross wind speed is some 47 feet above the line of sight 45 caliber 500 grain lead bullets had shooting 1000 yard matches in the late 1800's.</p></blockquote><p></p>
[QUOTE="Bart B, post: 1125202, member: 5302"] Here's another interesting thing about wind. The higher a bullet is above the line of sight, the greater the cross wind speeds will be. Consider this table I built using the formulas that helps people installing wind turbines for generating electricity: [IMG]http://i735.photobucket.com/albums/ww351/BartBob/eb601d71-8248-4d41-8ff6-384596b75328.jpg[/IMG] A .308 Win bullet will have a maximum ordinate of about 3 feet above the line of sight on its way to a 600 yard target. Same cartridge zeroed at 1000 yards, it's bullet goes about 11 feet above the line of sight to the target. For a .300 Win Mag, the maximum ordinates are about 2/3rds as much. Both maximum ordinates are about 55% of the zero range. If the cross wind's 15 mph fifteen feet above the line of sight across all the terrain types shown across their columns, the actual wind speed in the line of sight is shown in bold text. All of this is why the first 20 or so firing points at the west side of the 1000-yard range at Camp Perry were eventually not used. The tree line on the west side was so close to the first 20 or so shooters, they had a wind advantage of getting less cross winds from the west that those at the east side of the firing line some 70 firing points further from the tree line. As far as I know, none of this is used in software calculating wind drift for bullets. It all assumes the same crosswind speed for all bullet heights above the line of sight. I can imagine what the cross wind speed is some 47 feet above the line of sight 45 caliber 500 grain lead bullets had shooting 1000 yard matches in the late 1800's. [/QUOTE]
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Wind Drift; First Third vs. Last Third of Target Range
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