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Long Range Hunting & Shooting
MV Chronographs, Calculators and Accuracy
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<blockquote data-quote="Doom2" data-source="post: 2544634" data-attributes="member: 108323"><p>Most reputable ballistic calculators at 500 yds are going to give the same drop provided that the input data is the same. As noted atmospheric pressure is one of the most often misunderstood inputs. The calculations must use actual station pressure at the location. This is not the pressure reported in most weather reports which is barometric pressure corrected to sea level. If barometric pressure is used the actual elevation must be input. I'm not sure how Kestral handles this.</p><p></p><p>It also important to note that these programs utilize numerical integration. As such the actual results are dependent on the step size each programmer uses. This becomes a tradeoff between calculation speed and accuracy. </p><p></p><p>As for ballistic coefficient there is no industry standard for testing and reporting the ballistic coefficient. We don't now the actual distance/Mach range it applies. In many cases the drag model chosen doesn't even match the bullet geometry.</p><p></p><p>Ultimately any system (bullet, cartridge, rifle, and ballistic app) should be trued to actual data. Typically most center fired rifles can be trued to 600yds easily by varying the muzzle velocity (for lighter bullets like the 52-55gr I use 500yds). This works because typical variations in ballistic coefficient has a small effect. At longer ranges it's best to adjust the BC to match a known muzzle velocity.</p></blockquote><p></p>
[QUOTE="Doom2, post: 2544634, member: 108323"] Most reputable ballistic calculators at 500 yds are going to give the same drop provided that the input data is the same. As noted atmospheric pressure is one of the most often misunderstood inputs. The calculations must use actual station pressure at the location. This is not the pressure reported in most weather reports which is barometric pressure corrected to sea level. If barometric pressure is used the actual elevation must be input. I’m not sure how Kestral handles this. It also important to note that these programs utilize numerical integration. As such the actual results are dependent on the step size each programmer uses. This becomes a tradeoff between calculation speed and accuracy. As for ballistic coefficient there is no industry standard for testing and reporting the ballistic coefficient. We don’t now the actual distance/Mach range it applies. In many cases the drag model chosen doesn’t even match the bullet geometry. Ultimately any system (bullet, cartridge, rifle, and ballistic app) should be trued to actual data. Typically most center fired rifles can be trued to 600yds easily by varying the muzzle velocity (for lighter bullets like the 52-55gr I use 500yds). This works because typical variations in ballistic coefficient has a small effect. At longer ranges it’s best to adjust the BC to match a known muzzle velocity. [/QUOTE]
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