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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Effects of wind?
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<blockquote data-quote="Richard338" data-source="post: 80731" data-attributes="member: 1537"><p>JB, I flipped through McCoy's book and found explanations that might fit both our observations.</p><p>He says that a pure head or tail wind (with no crosswind) lowers or raises (respectively) the trajectory by a small amount.</p><p>This agrees with the calcs I ran. </p><p></p><p>What could explain what you saw is this business of the vertical component from a cross wind.</p><p>If a righthand twist barrel is zeroed at in calm conditons, then wind from the left will push the bullets to the right and down.</p><p>Wind from the right will push the bullets left and up. If the wind slowly changed, the string of bullets would form a slanted line (about 20 deg for many bullets, twists etc), going from top left to bottom right.</p><p></p><p>So if you had wind from the left when you got zeroed, then the wind switched to a headwind, the new headwind would want to lower the trajectory (only a small amount). But the loss of the vertical component from the crosswind (which switched away) would be a bigger effect, and the net result would be a raised trajectory.</p><p>Were your headwind gusts switching from a crosswind from the left?</p></blockquote><p></p>
[QUOTE="Richard338, post: 80731, member: 1537"] JB, I flipped through McCoy's book and found explanations that might fit both our observations. He says that a pure head or tail wind (with no crosswind) lowers or raises (respectively) the trajectory by a small amount. This agrees with the calcs I ran. What could explain what you saw is this business of the vertical component from a cross wind. If a righthand twist barrel is zeroed at in calm conditons, then wind from the left will push the bullets to the right and down. Wind from the right will push the bullets left and up. If the wind slowly changed, the string of bullets would form a slanted line (about 20 deg for many bullets, twists etc), going from top left to bottom right. So if you had wind from the left when you got zeroed, then the wind switched to a headwind, the new headwind would want to lower the trajectory (only a small amount). But the loss of the vertical component from the crosswind (which switched away) would be a bigger effect, and the net result would be a raised trajectory. Were your headwind gusts switching from a crosswind from the left? [/QUOTE]
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Effects of wind?
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