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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Do you guys dial in for spin drift?
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<blockquote data-quote="Bart B" data-source="post: 503182" data-attributes="member: 5302"><p>I've not seen any coriolis effect in either hemisphere from South Africa at 30 degrees south latitude to the Washington, DC area at about 40 degrees north latitude. Nobody else has either shooting their 30 (and smaller) calibers through 1000 yards. Shipboard naval gun fire computers I worked on had zero correction for both spin drift and coriolis up through 4000 yards; beyond that it grew a little bit for each 1000 yards of range.</p><p></p><p>I think they're fine when the best long range marksman on earth in International Palma competition all agree there's no significant effect.</p><p></p><p>Looks like your next quote's a blanket statement.</p><p></p><p>Are you convinced there wasn't a subtle crosswind invisible to the naked eye that caused that windage error? Did you do anything to see how much cross wind there was? And if you were shooting right-handed holding the rifle to your shoulder as it rested atop somthing on a bench, it's normal that heavier recoiling rounds shoot further to the right. The barrel moves that way while the bullet's going down the barrel.</p><p></p><p>David Tubb (many time Nat'l champ, US Palma Team member) didn't see any spin drift effect shooting 250-gr. bullets leaving at 2150 fps from his .308 Win. at 800 through 1000 yard targets in all directions. I specifically asked him about that at a match when I learned he used them. The rest of us used 190's or 200's and we didn't see any effect. But his 250's bucked the wind better than our lighter bullets leaving faster.</p><p></p><p>I and many others see no difference between the first shot from a cold bore to the 10th through 20th when the bore's very, very hot.</p><p></p><p>Spin drift ain't linear from zero to many yards down range. If it's 1/4th MOA at 1000 yards, it will be about 1/10th MOA (probably less) at 400. Spin drift's almost directly proportonal to the spinning object's spin axis angle change or drop per hundred yards. There's very little change from 0 to 400, quite a lot from 0 to 1000.</p><p></p><p>======================================</p><p></p><p>I know some folks are convinced that coriolis and spin drift are very noticable in their shooting events. Having shot with, and been one of, and sometimes out shot, the top ranked long range competitors in the USA (world, too, in International Palma and Goodwill Matches), none of us ever use, think about, discuss, adust for, nor even care about.....spin drift or coriolis. 'Tain't enough to be concerned about.</p></blockquote><p></p>
[QUOTE="Bart B, post: 503182, member: 5302"] I've not seen any coriolis effect in either hemisphere from South Africa at 30 degrees south latitude to the Washington, DC area at about 40 degrees north latitude. Nobody else has either shooting their 30 (and smaller) calibers through 1000 yards. Shipboard naval gun fire computers I worked on had zero correction for both spin drift and coriolis up through 4000 yards; beyond that it grew a little bit for each 1000 yards of range. I think they're fine when the best long range marksman on earth in International Palma competition all agree there's no significant effect. Looks like your next quote's a blanket statement. Are you convinced there wasn't a subtle crosswind invisible to the naked eye that caused that windage error? Did you do anything to see how much cross wind there was? And if you were shooting right-handed holding the rifle to your shoulder as it rested atop somthing on a bench, it's normal that heavier recoiling rounds shoot further to the right. The barrel moves that way while the bullet's going down the barrel. David Tubb (many time Nat'l champ, US Palma Team member) didn't see any spin drift effect shooting 250-gr. bullets leaving at 2150 fps from his .308 Win. at 800 through 1000 yard targets in all directions. I specifically asked him about that at a match when I learned he used them. The rest of us used 190's or 200's and we didn't see any effect. But his 250's bucked the wind better than our lighter bullets leaving faster. I and many others see no difference between the first shot from a cold bore to the 10th through 20th when the bore's very, very hot. Spin drift ain't linear from zero to many yards down range. If it's 1/4th MOA at 1000 yards, it will be about 1/10th MOA (probably less) at 400. Spin drift's almost directly proportonal to the spinning object's spin axis angle change or drop per hundred yards. There's very little change from 0 to 400, quite a lot from 0 to 1000. ====================================== I know some folks are convinced that coriolis and spin drift are very noticable in their shooting events. Having shot with, and been one of, and sometimes out shot, the top ranked long range competitors in the USA (world, too, in International Palma and Goodwill Matches), none of us ever use, think about, discuss, adust for, nor even care about.....spin drift or coriolis. 'Tain't enough to be concerned about. [/QUOTE]
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Do you guys dial in for spin drift?
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