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Reloading Techniques For Reloading


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sd and es

 
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Old 08-07-2010, 05:55 AM
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Join Date: Jul 2010
Posts: 22
sd and es

Can someone explain what SD and ES means I hear that alot involving reloading
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Old 08-07-2010, 06:13 AM
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Join Date: Oct 2007
Location: Mountians of SW NC, near Asheville
Posts: 1,596
Re: sd and es

ES = Extreme Spread.

For us, it simply means the difference beteen the fastest and slowest velocity of a tested string.


SD = Standard Deviation.

It's a statistical/mathmatical thing. Sorta equvilent to "averaqe" BUT not quite the same. More like an average difference of each bullet's speed when measured from the average speed of the tested string. (You get that? Not sure I do!) It's somewhat complex to calculate and very difficult to describe in a few words so just consider it a better way of measuring the quality of our load's vvelocity consistancy.


Neither factor is of much use in determining a loads accuracy potential at short ranges (inside 300 yd.s). It only affects longer range accuracy when small differences in velocity begin to show up as vertical stringing in the trajectory.

Last edited by boomtube; 08-07-2010 at 12:33 PM.
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