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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Pressure/temp vs trajctory
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<blockquote data-quote="sierra22" data-source="post: 34803" data-attributes="member: 949"><p>Yes, you all understand the intention with my question correctly. Complicated yes, but satisfactory fun if I can get it working.</p><p>True, sighters or several charts will take care of (parts of) the problem.</p><p></p><p>However, I know hard target interdiction operators correct their MOA on a "fill-in-the-blanks" formula using constants calculated for the various ranges, AND hitting their targets.</p><p></p><p>I have the data for the Raufoss .50 MP ammunition and I'm familiar with using the form and the calculator, but I don't understand the process of finding the variables that would be valid for other calibers than the .50.</p><p></p><p>To illustrate:</p><p>In the past I calculated a chart for the 600m range I sometimes use, but it was never "quite right" even though very, close. In winter it wasn't all that close.</p><p>On a mild winter day I'd get 52 instead of 48 clicks (1/3 MOA scope) for elevation. This I accredited to reduced powder burn rate.</p><p>For windage I could get about 41 instead of 37 clicks for windage (almost constant wind from the sea), which I accredited to poor wind calling.</p><p>Of course these errors would get larger with range, but 600m is all I have collected data for.</p><p>However, when I was taught some neat tricks and borrowed a wind/barometer/termometer, calculated the new BC it all got quite a bit closer. </p><p></p><p>A calculation could look like:</p><p>(stand. pressure: measured press.)x(m. temperature:stand. temp.)x manufacturers calc. BC</p><p>(1000:980)x(480,9:517,7)x0,458= 0,433 (BC corrected for pressure (in hPa, works same way for inches Hg if I understand the theory correct) and temperature (simple temperature measurement converted to Rankine).</p><p></p><p>[ 07-23-2004: Message edited by: sierra22 ]</p><p></p><p>[ 07-23-2004: Message edited by: sierra22 ]</p><p></p><p>[ 07-23-2004: Message edited by: sierra22 ]</p></blockquote><p></p>
[QUOTE="sierra22, post: 34803, member: 949"] Yes, you all understand the intention with my question correctly. Complicated yes, but satisfactory fun if I can get it working. True, sighters or several charts will take care of (parts of) the problem. However, I know hard target interdiction operators correct their MOA on a "fill-in-the-blanks" formula using constants calculated for the various ranges, AND hitting their targets. I have the data for the Raufoss .50 MP ammunition and I'm familiar with using the form and the calculator, but I don't understand the process of finding the variables that would be valid for other calibers than the .50. To illustrate: In the past I calculated a chart for the 600m range I sometimes use, but it was never "quite right" even though very, close. In winter it wasn't all that close. On a mild winter day I'd get 52 instead of 48 clicks (1/3 MOA scope) for elevation. This I accredited to reduced powder burn rate. For windage I could get about 41 instead of 37 clicks for windage (almost constant wind from the sea), which I accredited to poor wind calling. Of course these errors would get larger with range, but 600m is all I have collected data for. However, when I was taught some neat tricks and borrowed a wind/barometer/termometer, calculated the new BC it all got quite a bit closer. A calculation could look like: (stand. pressure: measured press.)x(m. temperature:stand. temp.)x manufacturers calc. BC (1000:980)x(480,9:517,7)x0,458= 0,433 (BC corrected for pressure (in hPa, works same way for inches Hg if I understand the theory correct) and temperature (simple temperature measurement converted to Rankine). [ 07-23-2004: Message edited by: sierra22 ] [ 07-23-2004: Message edited by: sierra22 ] [ 07-23-2004: Message edited by: sierra22 ] [/QUOTE]
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