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Long Range Hunting & Shooting
I need some reloading guidance concerning ES SD
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<blockquote data-quote="Schnyd112" data-source="post: 1716268" data-attributes="member: 90453"><p>How many rounds per group? Also, I don't think it is possible to have a SD higher than your extreme spread. Standard deviation is a measure of how far about any one shot may be from the average. Something like 70% of your shots are supposed to be inside 1 standard deviation from the mean, so that's a range of 2 standard deviations (that's statistics). Extreme spread is the difference between your highest and lowest, the extremes, so something is messed up in those numbers. </p><p></p><p>Those numbers are not bad, I shot competitions and won ribbons with a .220 that never had an extreme spread less than 40 FPS. Now, they aren't single digit SD, but that is the holy grail of numbers. Primers, primer depth, neck tension, annealing, all help to keep your numbers more consistent. But if it shoots well, why bother running every round over a chronograph to get numbers you don't need?</p><p></p><p>Finally, try h4064 in your .220 Swift. That's an old cartridge and it deserves an ancient powder.</p></blockquote><p></p>
[QUOTE="Schnyd112, post: 1716268, member: 90453"] How many rounds per group? Also, I don’t think it is possible to have a SD higher than your extreme spread. Standard deviation is a measure of how far about any one shot may be from the average. Something like 70% of your shots are supposed to be inside 1 standard deviation from the mean, so that’s a range of 2 standard deviations (that’s statistics). Extreme spread is the difference between your highest and lowest, the extremes, so something is messed up in those numbers. Those numbers are not bad, I shot competitions and won ribbons with a .220 that never had an extreme spread less than 40 FPS. Now, they aren’t single digit SD, but that is the holy grail of numbers. Primers, primer depth, neck tension, annealing, all help to keep your numbers more consistent. But if it shoots well, why bother running every round over a chronograph to get numbers you don’t need? Finally, try h4064 in your .220 Swift. That’s an old cartridge and it deserves an ancient powder. [/QUOTE]
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I need some reloading guidance concerning ES SD
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