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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Bullet stability calculation
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<blockquote data-quote="BryanLitz" data-source="post: 1132498" data-attributes="member: 7848"><p>ohiohunter,</p><p></p><p>Your observation of flyers likely has nothing to do with stability. There are many causes for flyers unrelated to stability.</p><p></p><p>RockyMtnMT,</p><p></p><p>The issue your having is that you're using barometric pressure in the JBM input. You mentioned using 29.98 inHg for 3000'. This is the barometric pressure, not an absolute or station pressure. The standard pressure for 3000' is 26.82 inHg. When you tell the Berger program 3000 feet altitude, it's using 26.82 inHg behind the scenes for the calculation.</p><p></p><p>The weather stations report barometric pressure, which is corrected for sea level. It's not accurate at any given point on the ground (how could it be, the weather station doesn't know how high up you are?) If you're using barometric pressure from the TV, you have to correct that to your altitude.</p><p></p><p>There's a sticky thread on this site (here it is: <a href="http://www.longrangehunting.com/forums/f19/altitude-vs-barometric-pressure-11950/" target="_blank">http://www.longrangehunting.com/forums/f19/altitude-vs-barometric-pressure-11950/</a> ) which explains this in more detail. It's a common misunderstanding in ballistics.</p><p></p><p>Take care,</p><p>-Bryan</p></blockquote><p></p>
[QUOTE="BryanLitz, post: 1132498, member: 7848"] ohiohunter, Your observation of flyers likely has nothing to do with stability. There are many causes for flyers unrelated to stability. RockyMtnMT, The issue your having is that you're using barometric pressure in the JBM input. You mentioned using 29.98 inHg for 3000'. This is the barometric pressure, not an absolute or station pressure. The standard pressure for 3000' is 26.82 inHg. When you tell the Berger program 3000 feet altitude, it's using 26.82 inHg behind the scenes for the calculation. The weather stations report barometric pressure, which is corrected for sea level. It's not accurate at any given point on the ground (how could it be, the weather station doesn't know how high up you are?) If you're using barometric pressure from the TV, you have to correct that to your altitude. There's a sticky thread on this site (here it is: [url]http://www.longrangehunting.com/forums/f19/altitude-vs-barometric-pressure-11950/[/url] ) which explains this in more detail. It's a common misunderstanding in ballistics. Take care, -Bryan [/QUOTE]
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Bullet stability calculation
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