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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Twist rate, how fast is too fast?
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<blockquote data-quote="HARPERC" data-source="post: 2457615" data-attributes="member: 30671"><p>My 6.5 Ultracat has a 1-6" twist, and runs the 124 grain Hammer Hunter 3960 fps. Roughly a 2.8 Sg. No issues with this bullet but a similar weight cup and core is unlikely to hold up.</p><p></p><p>If I read correctly JBM says an Sg of 1.3-1.5 is desirable for flight.</p><p></p><p>An article by Lytz indicates that 1.3 will lose about 6% of it's BC when compared to an Sg of 1.5.</p><p></p><p>Terminal performance depends somewhat on what you intend to terminate, and from what angle.</p><p></p><p>Some of the African DG cartridges do yield those higher numbers. I think the game involved explains that.</p><p></p><p>Personally I think an Sg of 2 is a good place to be. Not dogmatic or an absolute.</p><p></p><p></p><p>Velocity helps a little, the 156 Berger can reach that 1.5 stability in a 26 Nosler 1-8" twist, the smaller 6.5's not likely.</p></blockquote><p></p>
[QUOTE="HARPERC, post: 2457615, member: 30671"] My 6.5 Ultracat has a 1-6" twist, and runs the 124 grain Hammer Hunter 3960 fps. Roughly a 2.8 Sg. No issues with this bullet but a similar weight cup and core is unlikely to hold up. If I read correctly JBM says an Sg of 1.3-1.5 is desirable for flight. An article by Lytz indicates that 1.3 will lose about 6% of it's BC when compared to an Sg of 1.5. Terminal performance depends somewhat on what you intend to terminate, and from what angle. Some of the African DG cartridges do yield those higher numbers. I think the game involved explains that. Personally I think an Sg of 2 is a good place to be. Not dogmatic or an absolute. Velocity helps a little, the 156 Berger can reach that 1.5 stability in a 26 Nosler 1-8" twist, the smaller 6.5's not likely. [/QUOTE]
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Twist rate, how fast is too fast?
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