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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Bullet RPM Per Inch Math Problem
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<blockquote data-quote="Eric_F" data-source="post: 2100633" data-attributes="member: 105437"><p>Hmm ok that's easier, but will be a minimum limit as the bullet will definitely slow and spend more time into he animal.</p><p></p><p>Time in animal t (sec) = 1 ft / velocity (fps)</p><p>Rpm / 60 = rev/sec</p><p>So</p><p>Revolutions in animal = rpm/(60*velocity)</p><p></p><p>There are calculators for rpm at the muzzle, and I know Brian Litz has calculated how the spin slows over flight but I don't have his book so I'd use the muzzle rpm as your maximum. That's just muzzle velocity (fps) / twist rate (in per rev) / 12 in per foot * 60 sec/min.</p><p></p><p>If you're only using muzzle rpm, that simplifies to:</p><p>Rev in animal = muzzle velocity (fps) *12 in per foot / (impact velocity (fps) * twist (inches per rev))</p></blockquote><p></p>
[QUOTE="Eric_F, post: 2100633, member: 105437"] Hmm ok that's easier, but will be a minimum limit as the bullet will definitely slow and spend more time into he animal. Time in animal t (sec) = 1 ft / velocity (fps) Rpm / 60 = rev/sec So Revolutions in animal = rpm/(60*velocity) There are calculators for rpm at the muzzle, and I know Brian Litz has calculated how the spin slows over flight but I don't have his book so I'd use the muzzle rpm as your maximum. That's just muzzle velocity (fps) / twist rate (in per rev) / 12 in per foot * 60 sec/min. If you're only using muzzle rpm, that simplifies to: Rev in animal = muzzle velocity (fps) *12 in per foot / (impact velocity (fps) * twist (inches per rev)) [/QUOTE]
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Rifles, Reloading, Optics, Equipment
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Bullet RPM Per Inch Math Problem
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