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Reloading
Es and sd
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<blockquote data-quote="dsculley" data-source="post: 1174257" data-attributes="member: 77514"><p>Now that you have learned a bit about statistics, you can start applying it to your target and not just MV. You can take the group you shot with the SD of 8.66.</p><p></p><p>If your target doesn't have graph lines, you can take a square and draw a horizontal line under and vertical line beside your group. Measure the vertical and horizontal distance of each shot from the lines and record them. EG- I just started working on load development for a new build. I did this with my best group and got the following:</p><p></p><p> <u>Vert</u> <u>Horiz</u></p><p>Shot 1 0.443 0.773</p><p>Shot 2 0.542 0.180</p><p>Shot 3 1.005 0.385</p><p></p><p>(Only 3 shots, not really enough but will have to suffice for this demonstration.)</p><p></p><p>Subtract the smallest from the largest for each and you get Vert spread of 0.562 and Horiz spread of 0.593. It is a bit under but we well call it a 0.6" group. Now that sounds promising doesn't it? Based on this, many would call this a 0.6" gun.</p><p></p><p>Now lets apply a bit of statistics. Using these figures, I calculated the SD for both vertical and horizontal. and got .030" for each. 99% of the shots should fall within an area 3 SD's above the average and 3 SD's below the average. For this example I don't need to compute the averages because all I am concerned about is the total spread, which is the SD x 6 or 0.30 x 6 = 1.80. 1.80" doesn't sound nearly as good does it? As I said earlier, 3 shots is not really enough to be statistically significant. I will keep this information and combine it with future shots to keep adding to the sample. Now suppose that I fire 7 more rounds and keep them withing the 0.6" original group. I used some random numbers and recomputed base on a ten shot group that stayed within the spread of this group and got SD of 0.195. 6 x 0.195 = 1.17. Now that is sounding more promising!</p><p></p><p>The reason for this exercise is to show that the same principles that you use to evaluate muzzle velocity can be used in other practical ways as well. It is also a bit of an eye opener when you start applying this to your targets.</p><p></p><p>There is another observation you can make when using this. See how many shots are above the average and how many are below the average. If your hand loading technique is good and your use a good, repeatable shooting position so that your shooting technique is "precision" then you should see as many shots above as below the average. If not, something is "out of control". (Pulled shots, unsteady shooting position, loose scope, loose action screws, etc)</p><p></p><p>FWIW,</p><p></p><p>Dennis</p></blockquote><p></p>
[QUOTE="dsculley, post: 1174257, member: 77514"] Now that you have learned a bit about statistics, you can start applying it to your target and not just MV. You can take the group you shot with the SD of 8.66. If your target doesn't have graph lines, you can take a square and draw a horizontal line under and vertical line beside your group. Measure the vertical and horizontal distance of each shot from the lines and record them. EG- I just started working on load development for a new build. I did this with my best group and got the following: [U]Vert[/U] [U]Horiz[/U] Shot 1 0.443 0.773 Shot 2 0.542 0.180 Shot 3 1.005 0.385 (Only 3 shots, not really enough but will have to suffice for this demonstration.) Subtract the smallest from the largest for each and you get Vert spread of 0.562 and Horiz spread of 0.593. It is a bit under but we well call it a 0.6" group. Now that sounds promising doesn't it? Based on this, many would call this a 0.6" gun. Now lets apply a bit of statistics. Using these figures, I calculated the SD for both vertical and horizontal. and got .030" for each. 99% of the shots should fall within an area 3 SD's above the average and 3 SD's below the average. For this example I don't need to compute the averages because all I am concerned about is the total spread, which is the SD x 6 or 0.30 x 6 = 1.80. 1.80" doesn't sound nearly as good does it? As I said earlier, 3 shots is not really enough to be statistically significant. I will keep this information and combine it with future shots to keep adding to the sample. Now suppose that I fire 7 more rounds and keep them withing the 0.6" original group. I used some random numbers and recomputed base on a ten shot group that stayed within the spread of this group and got SD of 0.195. 6 x 0.195 = 1.17. Now that is sounding more promising! The reason for this exercise is to show that the same principles that you use to evaluate muzzle velocity can be used in other practical ways as well. It is also a bit of an eye opener when you start applying this to your targets. There is another observation you can make when using this. See how many shots are above the average and how many are below the average. If your hand loading technique is good and your use a good, repeatable shooting position so that your shooting technique is "precision" then you should see as many shots above as below the average. If not, something is "out of control". (Pulled shots, unsteady shooting position, loose scope, loose action screws, etc) FWIW, Dennis [/QUOTE]
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