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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Calculating B.C. with LabRadar. Tutorial on my method.
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<blockquote data-quote="entoptics" data-source="post: 2619350" data-attributes="member: 104268"><p>Your using one model based on drag coefficients to check another model based on ballistic coefficients, so it's hard to evaluate what's real (perhaps neither one is?), though there's nothing wrong with doing that thought experiment, and it provides useful insight.</p><p></p><p>What I can say is, those differences are relatively small in the scheme of things for extended hunting range. Using JBM's trajectory calculator, at 3000 fps, there's less than 2" POI difference at 700 yards (1 scope click), and only 50 fps velocity difference between a 0.341 and 0.362 G7 BC. Heck, it's only 5" and 65 fps at 1000 yards.</p><p></p><p>As another data point, I've got 89 LabRadar B.C. measurements of the 147 ELDM from my 264 WM, 1:8 twist, at similar velocities, and the average for me is 0.326 G7. I'm probably not a good enough shooter to tell the difference between 0.326 and 0.351 B.C. or 0.351 and 0.362. A 3 mph 90° wind vs 270° wind makes that much difference in the 4DOF app due to aerodynamic jump (I think that's why anyway). Using 0.326 in my calculator (Ballistic App) does seem to work pretty good for me though. I've tried 4DOF too, and it works pretty good too...</p><p></p><p>In summary, the variance among quality models <em>should be</em> relatively small, and your example demonstrates that nicely. It also demonstrates that a $750 consumer setup can get you within spitting distance of one of the world's most sophisticated ballistics laboratories.</p></blockquote><p></p>
[QUOTE="entoptics, post: 2619350, member: 104268"] Your using one model based on drag coefficients to check another model based on ballistic coefficients, so it's hard to evaluate what's real (perhaps neither one is?), though there's nothing wrong with doing that thought experiment, and it provides useful insight. What I can say is, those differences are relatively small in the scheme of things for extended hunting range. Using JBM's trajectory calculator, at 3000 fps, there's less than 2" POI difference at 700 yards (1 scope click), and only 50 fps velocity difference between a 0.341 and 0.362 G7 BC. Heck, it's only 5" and 65 fps at 1000 yards. As another data point, I've got 89 LabRadar B.C. measurements of the 147 ELDM from my 264 WM, 1:8 twist, at similar velocities, and the average for me is 0.326 G7. I'm probably not a good enough shooter to tell the difference between 0.326 and 0.351 B.C. or 0.351 and 0.362. A 3 mph 90° wind vs 270° wind makes that much difference in the 4DOF app due to aerodynamic jump (I think that's why anyway). Using 0.326 in my calculator (Ballistic App) does seem to work pretty good for me though. I've tried 4DOF too, and it works pretty good too... In summary, the variance among quality models [I]should be[/I] relatively small, and your example demonstrates that nicely. It also demonstrates that a $750 consumer setup can get you within spitting distance of one of the world's most sophisticated ballistics laboratories. [/QUOTE]
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Calculating B.C. with LabRadar. Tutorial on my method.
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