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Rifles, Reloading, Optics, Equipment
Reloading
Chronograph recomendations
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<blockquote data-quote="Forester" data-source="post: 208709" data-attributes="member: 11102"><p>If you re-test the load then you have effectively increased the sample size. For magnum loads or any load that heats the barrel too much I would just suggest waiting to let the barrel cool to the same point to prevent heat from changing the results. </p><p></p><p>I would not consider a sample of 3 to represent with any significant level of confidence the performance of a large number of rounds. You can get pretty deep into the statistics involved but to predict the performance of a large number of rounds, say 100, you need to test more than 3.</p><p></p><p>I am not saying SD is not a valid way to measure a loads consistency, simply that low ES is a tougher standard to meet, like using a 5 shot group instead of 3. My reason for using ES is mostly this; SD is a statistical way to predict deviation from the norm given a certain data set, ES is the actual observed velocity spread. I place more value on my actual measured numbers than on a prediction. </p><p></p><p>I don't mean to say that ES is the whole story, I suppose you could have a load with very consistent velocities but once in awhile throws one shot 100fps high or low...both the SD and ES might be fine, but I would not trust it.</p><p></p><p>The bottom line I think is you have to test and test and test to be sure that you won't get some unpleasant surprise on the shot that counts.</p></blockquote><p></p>
[QUOTE="Forester, post: 208709, member: 11102"] If you re-test the load then you have effectively increased the sample size. For magnum loads or any load that heats the barrel too much I would just suggest waiting to let the barrel cool to the same point to prevent heat from changing the results. I would not consider a sample of 3 to represent with any significant level of confidence the performance of a large number of rounds. You can get pretty deep into the statistics involved but to predict the performance of a large number of rounds, say 100, you need to test more than 3. I am not saying SD is not a valid way to measure a loads consistency, simply that low ES is a tougher standard to meet, like using a 5 shot group instead of 3. My reason for using ES is mostly this; SD is a statistical way to predict deviation from the norm given a certain data set, ES is the actual observed velocity spread. I place more value on my actual measured numbers than on a prediction. I don't mean to say that ES is the whole story, I suppose you could have a load with very consistent velocities but once in awhile throws one shot 100fps high or low...both the SD and ES might be fine, but I would not trust it. The bottom line I think is you have to test and test and test to be sure that you won't get some unpleasant surprise on the shot that counts. [/QUOTE]
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Chronograph recomendations
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