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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Bullet stabilization, strictly RPM?
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<blockquote data-quote="Mikecr" data-source="post: 170585" data-attributes="member: 1521"><p>There is a good article about it here:</p><p><a href="http://www.riflebarrels.com/articles/bullets_ballastics/effects_altitude_temperature_rifling_twist.htm" target="_blank">Lilja Precision Rifle Barrels - Articles: Effects of Altitude and Temperature on Rifling Twist</a></p><p></p><p>and here</p><p><a href="http://www.nennstiel-ruprecht.de/bullfly/index.htm" target="_blank">How do bullets fly?</a></p><p></p><p>some here</p><p><a href="http://www.exteriorballistics.com/ebexplained/5th/25.cfm" target="_blank">exterior ballistics</a></p><p></p><p>more</p><p><a href="http://en.wikipedia.org/wiki/Twist_rate" target="_blank">Twist rate - Wikipedia, the free encyclopedia</a></p><p></p><p>The best book I've read on it is 'Modern Exterior Ballistics' by R.L.McCoy. </p><p>This is not easy stuff to understand, or simplify. It is afterall, part of rocket science.</p><p>There is Greenhill, barrelmaker tables, and a few other rules of thumb out there. All will fail tests quickly, and some(like an nfa spreadsheet) are nothing more than monkey math. That is, they defined extremely narrow observations with math. Then put it out there as though it would work across the board. WRONG, anything outside that narrow window -falls apart completely.</p><p>Working on it for over 10yrs(very part-time), I have not been able to put together a rule of thumb which would pass all tests. I currently use McCoy's code(slightly modified) which also encompasses much of the math within JBM's calculators. </p><p><a href="http://www.eskimo.com/~jbm/calculations/calculations.html" target="_blank">JBM - Calculations</a></p><p>Even McCoy's math will not predict all. It will not pass ALL tests either. His testing was limited too, although not so much as for Greenhill. But it does take way more into account than ANY rule of thumb. </p><p>To perfect this area of science requires more testing, simple as that.</p></blockquote><p></p>
[QUOTE="Mikecr, post: 170585, member: 1521"] There is a good article about it here: [url=http://www.riflebarrels.com/articles/bullets_ballastics/effects_altitude_temperature_rifling_twist.htm]Lilja Precision Rifle Barrels - Articles: Effects of Altitude and Temperature on Rifling Twist[/url] and here [url=http://www.nennstiel-ruprecht.de/bullfly/index.htm]How do bullets fly?[/url] some here [url=http://www.exteriorballistics.com/ebexplained/5th/25.cfm]exterior ballistics[/url] more [url=http://en.wikipedia.org/wiki/Twist_rate]Twist rate - Wikipedia, the free encyclopedia[/url] The best book I've read on it is 'Modern Exterior Ballistics' by R.L.McCoy. This is not easy stuff to understand, or simplify. It is afterall, part of rocket science. There is Greenhill, barrelmaker tables, and a few other rules of thumb out there. All will fail tests quickly, and some(like an nfa spreadsheet) are nothing more than monkey math. That is, they defined extremely narrow observations with math. Then put it out there as though it would work across the board. WRONG, anything outside that narrow window -falls apart completely. Working on it for over 10yrs(very part-time), I have not been able to put together a rule of thumb which would pass all tests. I currently use McCoy's code(slightly modified) which also encompasses much of the math within JBM's calculators. [url=http://www.eskimo.com/~jbm/calculations/calculations.html]JBM - Calculations[/url] Even McCoy's math will not predict all. It will not pass ALL tests either. His testing was limited too, although not so much as for Greenhill. But it does take way more into account than ANY rule of thumb. To perfect this area of science requires more testing, simple as that. [/QUOTE]
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Bullet stabilization, strictly RPM?
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