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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Please help me with some ballistics calculations
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<blockquote data-quote="entoptics" data-source="post: 2268281" data-attributes="member: 104268"><p>Unless I'm making a math mistake somewhere, I don't think this is true...</p><p></p><p>Assume a cylindrical projectile (not a pointy bullet, but concept is the same) and a density of lead of 11.29 g/cm3. The frontal area of the cylinder is fixed since the bullet diameter is fixed, so...</p><p></p><p><strong><em>120 grain cylinder</em></strong></p><p>Side area = 0.3269 cm2</p><p></p><p><strong><em>139 grain cylinder</em></strong></p><p>Side area - 0.3787 cm2</p><p></p><p>Mass ratio - 139/120 = 115.8%</p><p>Side area ratio - 0.3787/0.3269 = 115.8%</p><p></p><p>I feel like I'm wrong, but triple checked my math, so I'm inclined to think something else is at play here...</p><p></p><p>Obviously, for forward motion, the ratio does change. 1 to 1 frontal area ratio, vs 1 to 1.158 mass ratio, so more mass per drag makes sense in drop data, but not wind.</p><p></p><p><img class="smilie smilie--emoji" loading="lazy" alt="🤔" title="Thinking face :thinking:" src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f914.png" data-shortname=":thinking:" /></p></blockquote><p></p>
[QUOTE="entoptics, post: 2268281, member: 104268"] Unless I'm making a math mistake somewhere, I don't think this is true... Assume a cylindrical projectile (not a pointy bullet, but concept is the same) and a density of lead of 11.29 g/cm3. The frontal area of the cylinder is fixed since the bullet diameter is fixed, so... [B][I]120 grain cylinder[/I][/B] Side area = 0.3269 cm2 [B][I]139 grain cylinder[/I][/B] Side area - 0.3787 cm2 Mass ratio - 139/120 = 115.8% Side area ratio - 0.3787/0.3269 = 115.8% I feel like I'm wrong, but triple checked my math, so I'm inclined to think something else is at play here... Obviously, for forward motion, the ratio does change. 1 to 1 frontal area ratio, vs 1 to 1.158 mass ratio, so more mass per drag makes sense in drop data, but not wind. 🤔 [/QUOTE]
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Rifles, Reloading, Optics, Equipment
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Please help me with some ballistics calculations
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