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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Effects of wind?
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<blockquote data-quote="jb1000br" data-source="post: 80622" data-attributes="member: 1459"><p>[ QUOTE ]</p><p>JB, why do you say it spends more time climbing?</p><p>I ran a trajectory calc on JBM's page using 3000fps and a BC of .7.</p><p>The apogee of a 1000 yard zeroed trajectory is at 540 yards, but that occurs at less than half the time for the 1000 yards trajectory because the bullet is going faster at first.</p><p>I added 20 mph head/tail winds and got predicted lower POI for headwind and raised POI for tailwind.</p><p>I had a clear example of a switching head/tail wind at 1000 yards a couple of weeks ago and definately found this to be the case.</p><p>Target rifle shooters have a memory trick "heads-up, and tails down" (as in aim up in a head wind, and aim lower for a tail wind).</p><p>The effect is small in any case but can get you. </p><p></p><p>[/ QUOTE ]</p><p></p><p>Richard -- first, forget computer models for this discussion.</p><p></p><p>I guess i should have been more specific, but left out something</p><p></p><p>seems TO ME the less flat the traj, the more likely to rise at 1K with a headwind.</p><p></p><p>It has been observed by those i trust with a 308 and 260, and myself with a 6br.</p><p></p><p>my 6.5-284 has not been noticably affected my any head/tailwinds encountered at 1K thus far.</p><p></p><p>IMO 3000fps with a .7BC is FLAT-*** traj and many rounds we use cant touch that.</p><p></p><p>in my mind, i see a flatter shooting round more likely to drop in a headwind, and a round with more drop getting loft.</p><p></p><p>Like i said -- it depends on too many things to make a rule like "heads up whatever down..."</p><p></p><p>Also, by "more time" i actually meant distance, and you just showed that was true, even with the flat shooter. 540 compared to 460 -- thats an 80yd diff</p><p></p><p>IMHO, and YMMV,</p><p>JB /ubbthreads/images/graemlins/smile.gif</p></blockquote><p></p>
[QUOTE="jb1000br, post: 80622, member: 1459"] [ QUOTE ] JB, why do you say it spends more time climbing? I ran a trajectory calc on JBM's page using 3000fps and a BC of .7. The apogee of a 1000 yard zeroed trajectory is at 540 yards, but that occurs at less than half the time for the 1000 yards trajectory because the bullet is going faster at first. I added 20 mph head/tail winds and got predicted lower POI for headwind and raised POI for tailwind. I had a clear example of a switching head/tail wind at 1000 yards a couple of weeks ago and definately found this to be the case. Target rifle shooters have a memory trick "heads-up, and tails down" (as in aim up in a head wind, and aim lower for a tail wind). The effect is small in any case but can get you. [/ QUOTE ] Richard -- first, forget computer models for this discussion. I guess i should have been more specific, but left out something seems TO ME the less flat the traj, the more likely to rise at 1K with a headwind. It has been observed by those i trust with a 308 and 260, and myself with a 6br. my 6.5-284 has not been noticably affected my any head/tailwinds encountered at 1K thus far. IMO 3000fps with a .7BC is FLAT-*** traj and many rounds we use cant touch that. in my mind, i see a flatter shooting round more likely to drop in a headwind, and a round with more drop getting loft. Like i said -- it depends on too many things to make a rule like "heads up whatever down..." Also, by "more time" i actually meant distance, and you just showed that was true, even with the flat shooter. 540 compared to 460 -- thats an 80yd diff IMHO, and YMMV, JB [img]/ubbthreads/images/graemlins/smile.gif[/img] [/QUOTE]
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