RDF-KY Posted February 5, 2008 Share Posted February 5, 2008 What does this mean? Does the lower spread mean the best? What does Standard Deviation mean? What is best when reloading? Link to comment Share on other sites More sharing options...
AikiDale Posted February 5, 2008 Share Posted February 5, 2008 Extreme spread is a reference to the fastest and slowest velocity measured by your chronograph. Standard Deviation is....look here: http://en.wikipedia.org/wiki/Standard_Deviation Link to comment Share on other sites More sharing options...
Flatland Shooter Posted February 5, 2008 Share Posted February 5, 2008 (edited) The lower the Standard Deviation the more consistent your loads are performing. Where it comes into play is assisting you in selecting loads to make a certain power factor. From information gleened from other sources on the forum, to assure 99%+ of your loads make major, you would want the velocity of your load to be 3 SD's higher than the minimum needed to make your power factor. For a major load that uses 165 grain bullets you need a velocity of 1000 fps. If your chronograph indicates you have a SD of 10 fps, you would want to consider loads where the velocity is 1000 fps plus 3 times the SD of 10 for a velocity of 1030. If your loads have a SD of 30 fps, you may need to load up at 1090 fps to be confident. So a load with a low SD can be loaded closer to the 165 PF than a load with a high SD, and still be confident it will make major. Bill edited because I can't type when I'm sleepy. Good night. Edited February 5, 2008 by Flatland Shooter Link to comment Share on other sites More sharing options...
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