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ballistic software question
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<blockquote data-quote="paphil" data-source="post: 490279" data-attributes="member: 17745"><p>One of the handy things taught at The Best of the West shooting school is the simple math to correct for changes in elevation and temperature. This works well for high BC bullets in pretty much big game hunting situations. It might not be fine tuned enough for prarrie dogs, but is not far off. For the first 500 yards, the point of impact won't change much at all, less than a couple of inches . AT 1000 yards, POI will raise or lower by 1/3 minute for each 1000 feet elevation or 20 degrees F temperature change. At 750 yards, it is half that or 1/6 th minute. </p><p> So if you are shooting a 7mm mag at 3000fps(berger 168, bc. 617) at 1000 feet elevation and 80 degrees and you are dead on at 100 or 200 or what ever and have developed your drop chart so it is right on out to 1000 yards. We now take that gun up to 7000 feet and 20 degrees. The air has gotten thinner because of the 6000 feet change in elevation but it also got denser due to the temperatures 60 degree drop. At 1000 yards, the elevation change is worth 2 minutes down and the 60 degree temperature will be worth 1 minute up. The net change is one minute(the gun will shoot high) or 10 inches at 1000 yards and 1/2 minute at 750 yards which is 3 1/4 inches. The temperature and altitude partially cancel each other out. </p><p> The lower the BC and velocity the greater the change so choose the highest possible BC. Run the numbers on the free calculator at the BOTW web site and have fun shooting!!</p></blockquote><p></p>
[QUOTE="paphil, post: 490279, member: 17745"] One of the handy things taught at The Best of the West shooting school is the simple math to correct for changes in elevation and temperature. This works well for high BC bullets in pretty much big game hunting situations. It might not be fine tuned enough for prarrie dogs, but is not far off. For the first 500 yards, the point of impact won't change much at all, less than a couple of inches . AT 1000 yards, POI will raise or lower by 1/3 minute for each 1000 feet elevation or 20 degrees F temperature change. At 750 yards, it is half that or 1/6 th minute. So if you are shooting a 7mm mag at 3000fps(berger 168, bc. 617) at 1000 feet elevation and 80 degrees and you are dead on at 100 or 200 or what ever and have developed your drop chart so it is right on out to 1000 yards. We now take that gun up to 7000 feet and 20 degrees. The air has gotten thinner because of the 6000 feet change in elevation but it also got denser due to the temperatures 60 degree drop. At 1000 yards, the elevation change is worth 2 minutes down and the 60 degree temperature will be worth 1 minute up. The net change is one minute(the gun will shoot high) or 10 inches at 1000 yards and 1/2 minute at 750 yards which is 3 1/4 inches. The temperature and altitude partially cancel each other out. The lower the BC and velocity the greater the change so choose the highest possible BC. Run the numbers on the free calculator at the BOTW web site and have fun shooting!! [/QUOTE]
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