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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Ballistic Program Inconsistencies
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<blockquote data-quote="BryanLitz" data-source="post: 311751" data-attributes="member: 7848"><p>Kyle,</p><p>Of the programs you listed, I'm only familiar with AlBal. I downloaded it some time ago and have compared it to my program and JBM and found it to be in close agreement. </p><p></p><p>Here's the case I run:</p><p></p><p>caliber: .308</p><p>Bullet 155 grain</p><p>G7 BC = .230</p><p>MV = 3000 fps</p><p>sight height = 1.5"</p><p>zero range = 100 yards</p><p>air temp = 59F</p><p>air press = 29.92 inHg</p><p>humidity = 0</p><p>(these are ICAO standard sea level conditions)</p><p></p><p>Those conditions produce the following outputs in 3 programs:</p><p>Bullet path at 1000 yards:</p><p>JBM: -317.6"</p><p>Point Mass Ballistics (my program): -317.74"</p><p>AlBal: -317.75"</p><p></p><p>I consider all 3 of these to be practically equal. They're all using the same atmosphere, and interpreting BC the same way.</p><p></p><p>It's not surprising to me that programs based on the Pejsa method would produce different answers, as that method doesn't interpret BC in a conventional way (thus the requirement for the additional variable; the '****** coefficient' or 'drag coefficient' as it's called in different applications).</p><p></p><p>If you have easy access to those other programs on your list, I'd be curious to see how their predictions compared to the above for a similar input set.</p><p></p><p>-Bryan</p></blockquote><p></p>
[QUOTE="BryanLitz, post: 311751, member: 7848"] Kyle, Of the programs you listed, I'm only familiar with AlBal. I downloaded it some time ago and have compared it to my program and JBM and found it to be in close agreement. Here's the case I run: caliber: .308 Bullet 155 grain G7 BC = .230 MV = 3000 fps sight height = 1.5" zero range = 100 yards air temp = 59F air press = 29.92 inHg humidity = 0 (these are ICAO standard sea level conditions) Those conditions produce the following outputs in 3 programs: Bullet path at 1000 yards: JBM: -317.6" Point Mass Ballistics (my program): -317.74" AlBal: -317.75" I consider all 3 of these to be practically equal. They're all using the same atmosphere, and interpreting BC the same way. It's not surprising to me that programs based on the Pejsa method would produce different answers, as that method doesn't interpret BC in a conventional way (thus the requirement for the additional variable; the '****** coefficient' or 'drag coefficient' as it's called in different applications). If you have easy access to those other programs on your list, I'd be curious to see how their predictions compared to the above for a similar input set. -Bryan [/QUOTE]
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Ballistic Program Inconsistencies
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