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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="Buffalobob" data-source="post: 190471" data-attributes="member: 8"><p>The adiabatic lapse rate is 5 degrees F per thousand feet.</p><p></p><p>If you are shooting up hill with a thousand feet elevation change then you have a temperature change affecting air density that causes a bullet to be 0.25 inches low at 1000 yards and you have an altitude effect on air density that causes the bullet to be 1.0 inch high at 1000 yards. The net affect is you will be 0. 75 inches high.</p><p></p><p>If you are shooting downhill with an altitude change of 1000 ft then the bullet will be .25 inches high due to the increase temperatures changing air density and it will be 1 inch low due to the altitude changing air density. and the result will be 0.75 inches low at 1000 yards.</p><p></p><p>If there is an inversion layer between you and the elk and the temperature is actually colder below the inversion then you will simply have to decide whether whether a 0.25 inch error in point of impact is important to you . The good news is that inversions occur when there is very little wind so you won't have to worry about the wind when shooting through an inversion. </p><p></p><p>The adjsutment factors I gave you in the first post were derived by running the ballistics repeatedly in JBM with changes in altitude while holding temperature constant and then running with constant altitude but different temperatures. They were developed for 1000 yards.</p><p></p><p>Now then if you are truly interested in 2000 yards then you should realize that the potential change in BC of the 200 grain Wildcat may be more of an unknown than the question you are asking. When you actually get you a rifle feel free to PM me and I will discuss my real results with you.</p></blockquote><p></p>
[QUOTE="Buffalobob, post: 190471, member: 8"] The adiabatic lapse rate is 5 degrees F per thousand feet. If you are shooting up hill with a thousand feet elevation change then you have a temperature change affecting air density that causes a bullet to be 0.25 inches low at 1000 yards and you have an altitude effect on air density that causes the bullet to be 1.0 inch high at 1000 yards. The net affect is you will be 0. 75 inches high. If you are shooting downhill with an altitude change of 1000 ft then the bullet will be .25 inches high due to the increase temperatures changing air density and it will be 1 inch low due to the altitude changing air density. and the result will be 0.75 inches low at 1000 yards. If there is an inversion layer between you and the elk and the temperature is actually colder below the inversion then you will simply have to decide whether whether a 0.25 inch error in point of impact is important to you . The good news is that inversions occur when there is very little wind so you won't have to worry about the wind when shooting through an inversion. The adjsutment factors I gave you in the first post were derived by running the ballistics repeatedly in JBM with changes in altitude while holding temperature constant and then running with constant altitude but different temperatures. They were developed for 1000 yards. Now then if you are truly interested in 2000 yards then you should realize that the potential change in BC of the 200 grain Wildcat may be more of an unknown than the question you are asking. When you actually get you a rifle feel free to PM me and I will discuss my real results with you. [/QUOTE]
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Help: Gun vs.Target - steep shots, barometric adjustments with big elevation change?
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