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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
.220 Swift - Non Lead - 1:14 twist
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<blockquote data-quote="Mikecr" data-source="post: 2159946" data-attributes="member: 1521"><p>Then allow me to speak more on improving stability with velocity increases.</p><p>With my earlier example:</p><p><u>in 14tw</u></p><p>Sg = 1.06 at 2kfps</p><p>Sg = 1.11 at 3kfps</p><p></p><p>Sg of 1.06 is barely stable, and if your air density bumps one day you could dip to <1.00 (where bullets will tumble).</p><p>So maybe you're advised that this will still work at higher velocities, and sure enough 3kfps MV does raise Sg back to marginally stable. The bullets impact point forward now, and that certainly is a big affect.</p><p>But you should know that it's a poor plan to be on that edge. That marginal stability holds detrimental affects to BC, and accuracy.</p><p>And regardless of velocity, that bullet/twist combo would never reach better than marginal stability under SL std air densities.</p><p></p><p>Ideally your Sg would be around 1.5, and with this, velocity will not make one bit of difference about anything stability-wise.</p><p>It's a goal you should be solving your plan for.</p><p></p><p>Notions about matching RPMs to work around actual stability requirements will lead you to failed tests.</p><p>Go ahead and explore it with credible calcs. You will see this. No need to believe me at all.</p><p>I am just trying to help you see this.</p></blockquote><p></p>
[QUOTE="Mikecr, post: 2159946, member: 1521"] Then allow me to speak more on improving stability with velocity increases. With my earlier example: [U]in 14tw[/U] Sg = 1.06 at 2kfps Sg = 1.11 at 3kfps Sg of 1.06 is barely stable, and if your air density bumps one day you could dip to <1.00 (where bullets will tumble). So maybe you're advised that this will still work at higher velocities, and sure enough 3kfps MV does raise Sg back to marginally stable. The bullets impact point forward now, and that certainly is a big affect. But you should know that it's a poor plan to be on that edge. That marginal stability holds detrimental affects to BC, and accuracy. And regardless of velocity, that bullet/twist combo would never reach better than marginal stability under SL std air densities. Ideally your Sg would be around 1.5, and with this, velocity will not make one bit of difference about anything stability-wise. It's a goal you should be solving your plan for. Notions about matching RPMs to work around actual stability requirements will lead you to failed tests. Go ahead and explore it with credible calcs. You will see this. No need to believe me at all. I am just trying to help you see this. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
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.220 Swift - Non Lead - 1:14 twist
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