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Rifles, Reloading, Optics, Equipment
Reloading
Standard Deviation
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<blockquote data-quote="Doom2" data-source="post: 2639216" data-attributes="member: 108323"><p>By my estimates you are looking at 95% of your rounds deviating +/- 6" due to velocity (I assumed 2000 ft elev). In comparison at 1200yds that's equivalent to misreading the wind by 1mph. Its likely you will miss the vital zone due to wind in the horizontal. You are also looking at 1-1/2 seconds of fligh time. A lot can happen in that time and you are losing a lot of energy at that range. I personally don't think I would be willing to risk that shot.</p><p></p><p>Depending on your location and terrain vertical wind and temperature variations may be more of issue that SD.</p><p></p><p>But to your question about number of rounds, let me answer it this way:</p><p> Shoot 10 rounds measure 3100 fps average 10fps SD, 95% confidence interval 3093-3107 fps SD 6.9-18.3 fps</p><p> Shoot 20 rounds measure 3100 fps average 10fps SD, 95% confidence interval 3095-3105 fps SD 7.6-14.6 fps</p><p></p><p>Another way to look at it is you would need to have a 5.5 SD over 10 rounds or a 7 SD over 20 rounds to have a 95% confidence that you have a true 10 SD.</p></blockquote><p></p>
[QUOTE="Doom2, post: 2639216, member: 108323"] By my estimates you are looking at 95% of your rounds deviating +/- 6" due to velocity (I assumed 2000 ft elev). In comparison at 1200yds that's equivalent to misreading the wind by 1mph. Its likely you will miss the vital zone due to wind in the horizontal. You are also looking at 1-1/2 seconds of fligh time. A lot can happen in that time and you are losing a lot of energy at that range. I personally don't think I would be willing to risk that shot. Depending on your location and terrain vertical wind and temperature variations may be more of issue that SD. But to your question about number of rounds, let me answer it this way: Shoot 10 rounds measure 3100 fps average 10fps SD, 95% confidence interval 3093-3107 fps SD 6.9-18.3 fps Shoot 20 rounds measure 3100 fps average 10fps SD, 95% confidence interval 3095-3105 fps SD 7.6-14.6 fps Another way to look at it is you would need to have a 5.5 SD over 10 rounds or a 7 SD over 20 rounds to have a 95% confidence that you have a true 10 SD. [/QUOTE]
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Standard Deviation
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