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Rifles, Reloading, Optics, Equipment
Reloading
Are these tumbling? 225 gr Hornady BTHP's in 300 WM
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<blockquote data-quote="westcliffe01" data-source="post: 806677" data-attributes="member: 35183"><p>Stability is RPM dependent. The actual RPM's can be achieved by various means, such as shooting at a lower speed through a faster twist rate, or a higher speed through a slower twist rate.</p><p></p><p>For a given twist rate, a higher MV will provide increased stability. The Berger stability calculator will show that. However, the difference between a 20" barrel and a 28" barrel should not make that much practical difference to stability, although it will make a difference to downrange energy.</p><p></p><p>For grins, I ran some numbers on the Berger stability calculator. Hornady does not state the bullet length, nor do they recommend a twist rate (kinda hard to believe from a premier bullet maker), so I looked up the length of a Berger target bullet of a similar weight (1.6"). I then ran the calc as follows:</p><p>Caliber 308</p><p>Weight 225gr</p><p>bullet length 1.6"</p><p>Barrel twist 10</p><p>Muzzle Velocity 2500fps</p><p>Temperature 20F</p><p>altitude 0feet</p><p></p><p>The calculated SG was 1.34 , for 60F and 1000ft it was 1.5 1.5 is "comfortable stability" and you should really do better than 2400fps unless you are being handicapped by that short barrel.</p><p></p><p>"corrected base cartridge"</p></blockquote><p></p>
[QUOTE="westcliffe01, post: 806677, member: 35183"] Stability is RPM dependent. The actual RPM's can be achieved by various means, such as shooting at a lower speed through a faster twist rate, or a higher speed through a slower twist rate. For a given twist rate, a higher MV will provide increased stability. The Berger stability calculator will show that. However, the difference between a 20" barrel and a 28" barrel should not make that much practical difference to stability, although it will make a difference to downrange energy. For grins, I ran some numbers on the Berger stability calculator. Hornady does not state the bullet length, nor do they recommend a twist rate (kinda hard to believe from a premier bullet maker), so I looked up the length of a Berger target bullet of a similar weight (1.6"). I then ran the calc as follows: Caliber 308 Weight 225gr bullet length 1.6" Barrel twist 10 Muzzle Velocity 2500fps Temperature 20F altitude 0feet The calculated SG was 1.34 , for 60F and 1000ft it was 1.5 1.5 is "comfortable stability" and you should really do better than 2400fps unless you are being handicapped by that short barrel. "corrected base cartridge" [/QUOTE]
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Are these tumbling? 225 gr Hornady BTHP's in 300 WM
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