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Long Range Hunting & Shooting
Elevation effects on bullet trajectory
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<blockquote data-quote="LRNut" data-source="post: 2133122" data-attributes="member: 3230"><p>I watched the first 1/3 of that video; completely misleading. There is no way you are going to be a mil high at 1000 yards based on a 20 deg temp change. I ran his load through JBM; a 20 diff results in .6 MOA less drop at 1000 yards. When I left the video, he was getting ready to explain "internal ballistics" - I assume he is going to blame a 20 deg difference for most of the effects of a high hit (higher MV). He needs to shoot temp insensitive powders if he is getting enough MV diff to cause a hit that high at 1000 yards.</p><p></p><p>Not sure if he addressed it in his video, but one way to combat the effects of a changing conditions is to shoot a high BC bullet. I just ran the same numbers on a Berger 195 7mm at 3000 fps; a 20 deg temp change results in .2 MOA difference at 1000 yards. </p><p></p><p>Most shooters think BC is a static number, but it changes as environmental conditions and velocity change. If you plot BC vs drop, you will find bullets with a very high BC don't perform much better than another with a BC .05 higher. But run the same comparison with a low BC bullet, and you will see a marked change. Thus, changes in temperature have a much greater impact on low BC bullets than high BC bullets.</p><p></p><p>FWIW, I don't find humidity changes to be a big issue; JBM confirms that - the Berger above drops .1 MOA less in 100% humidity than 0% humidity. Elevation changes are by and away the most important.</p></blockquote><p></p>
[QUOTE="LRNut, post: 2133122, member: 3230"] I watched the first 1/3 of that video; completely misleading. There is no way you are going to be a mil high at 1000 yards based on a 20 deg temp change. I ran his load through JBM; a 20 diff results in .6 MOA less drop at 1000 yards. When I left the video, he was getting ready to explain "internal ballistics" - I assume he is going to blame a 20 deg difference for most of the effects of a high hit (higher MV). He needs to shoot temp insensitive powders if he is getting enough MV diff to cause a hit that high at 1000 yards. Not sure if he addressed it in his video, but one way to combat the effects of a changing conditions is to shoot a high BC bullet. I just ran the same numbers on a Berger 195 7mm at 3000 fps; a 20 deg temp change results in .2 MOA difference at 1000 yards. Most shooters think BC is a static number, but it changes as environmental conditions and velocity change. If you plot BC vs drop, you will find bullets with a very high BC don't perform much better than another with a BC .05 higher. But run the same comparison with a low BC bullet, and you will see a marked change. Thus, changes in temperature have a much greater impact on low BC bullets than high BC bullets. FWIW, I don't find humidity changes to be a big issue; JBM confirms that - the Berger above drops .1 MOA less in 100% humidity than 0% humidity. Elevation changes are by and away the most important. [/QUOTE]
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