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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
BEWARE, Problems with Exbal and G7 BC's
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<blockquote data-quote="ericpetritz" data-source="post: 448312" data-attributes="member: 5958"><p>I sent Mr. Perry from Exbal an email asking him what atmospheric standard Exbal uses. Here is his response:</p><p></p><p>"Eric;</p><p></p><p>ICAO has a sea level pressure 29.92 and by definition of ICAO it is bone dry air (ie no humidity). ASM has a sea level pressure of 29.53 and 78% humidity by definition. ASM is the standard set by US Army Aberdeen proving grounds long ago. Half of the vendors use ASM and half use ICAO. The statement that a BC value calculated for ICAO is different than a BC calculated for ASM is misleading. BC is the ratio of how far a given bullet travels in one second to how far the standard bullet travels in one second. This ratio will not change with ASM or ICAO. Trajectory calculations are a different matter. you can play with humidity and pressure at sea level and see the difference.</p><p></p><p> </p><p></p><p>Exbal use default values of 29.92 pressure and 78% humidity at sea level so it is a hybrid solution.</p><p></p><p>Gerald L. Perry "</p></blockquote><p></p>
[QUOTE="ericpetritz, post: 448312, member: 5958"] I sent Mr. Perry from Exbal an email asking him what atmospheric standard Exbal uses. Here is his response: "Eric; ICAO has a sea level pressure 29.92 and by definition of ICAO it is bone dry air (ie no humidity). ASM has a sea level pressure of 29.53 and 78% humidity by definition. ASM is the standard set by US Army Aberdeen proving grounds long ago. Half of the vendors use ASM and half use ICAO. The statement that a BC value calculated for ICAO is different than a BC calculated for ASM is misleading. BC is the ratio of how far a given bullet travels in one second to how far the standard bullet travels in one second. This ratio will not change with ASM or ICAO. Trajectory calculations are a different matter. you can play with humidity and pressure at sea level and see the difference. Exbal use default values of 29.92 pressure and 78% humidity at sea level so it is a hybrid solution. Gerald L. Perry " [/QUOTE]
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BEWARE, Problems with Exbal and G7 BC's
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