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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Help: Gun vs.Target - steep shots, barometric adjustments with big elevation change?
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<blockquote data-quote="mattj" data-source="post: 190450" data-attributes="member: 8758"><p>I think he's specifically wondering how much the barometric pressure difference between the two altitudes (altitude of shooter vs altitude of target) will affect the shot (for really long shots at angles where the altitude difference seems significant). </p><p></p><p>I think he understands the drop difference induced by gravity/geometry, but he's specifically wondering how much difference just the barometric pressure difference between shooter location and target location (and the air in between) makes. This isn't something I've seen addressed anywhere, and something that none of the ballistics packages I'm aware of account for.</p><p></p><p>My gut feeling is that the effect on the actual effect ballistics will be relatively insignificant. I think to get some idea of the scale of the error the baro difference would induce, you could calculate the dope with ballistics software for a level shot at a standard baro pressure for 10,000 feet, then calculate the dope for the same shot with baro pressure that is standard at 9,000 feet or something. If the drop difference between the two at 1,000 yards or something is relatively small, then it's probably not worth worrying about. If it amounts to a quarter MOA or more, then it might be worth trying to compensate for. I would think that if you split the difference between the baro pressure at your current alt and the estimated pressure at the target's alt and plugged that pressure into your ballistics package, that the result would be a pretty decent approximation.</p></blockquote><p></p>
[QUOTE="mattj, post: 190450, member: 8758"] I think he's specifically wondering how much the barometric pressure difference between the two altitudes (altitude of shooter vs altitude of target) will affect the shot (for really long shots at angles where the altitude difference seems significant). I think he understands the drop difference induced by gravity/geometry, but he's specifically wondering how much difference just the barometric pressure difference between shooter location and target location (and the air in between) makes. This isn't something I've seen addressed anywhere, and something that none of the ballistics packages I'm aware of account for. My gut feeling is that the effect on the actual effect ballistics will be relatively insignificant. I think to get some idea of the scale of the error the baro difference would induce, you could calculate the dope with ballistics software for a level shot at a standard baro pressure for 10,000 feet, then calculate the dope for the same shot with baro pressure that is standard at 9,000 feet or something. If the drop difference between the two at 1,000 yards or something is relatively small, then it's probably not worth worrying about. If it amounts to a quarter MOA or more, then it might be worth trying to compensate for. I would think that if you split the difference between the baro pressure at your current alt and the estimated pressure at the target's alt and plugged that pressure into your ballistics package, that the result would be a pretty decent approximation. [/QUOTE]
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Help: Gun vs.Target - steep shots, barometric adjustments with big elevation change?
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