03-02-2019, 02:43 AM
Using Berger Bullet's twist rate stability calculator, a 12" bbl with a 1:8 twist launching Berger's 6.5mm 130 AR Hybrid bullet at 2000 fps at 0 altitude and in 0°F temperature is stable (think the coast of Alaska in winter).
Lighter bullets will also be fine, of course.
Using the same setup with Berger's 140 Hunter Elite at 1900 fps loses 2% BC in a 1:7.5 twist and 8% in a 1:8 twist barrel.
So, a 1:7.5 twist will lose 6% less BC if you're shooting 140-grain bullets in winter at sea level than a 1:8 twist.
Lighter bullets will also be fine, of course.
Using the same setup with Berger's 140 Hunter Elite at 1900 fps loses 2% BC in a 1:7.5 twist and 8% in a 1:8 twist barrel.
So, a 1:7.5 twist will lose 6% less BC if you're shooting 140-grain bullets in winter at sea level than a 1:8 twist.
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:: I Drank the Water :: Revelation 21:6 ::
:: I Drank the Water :: Revelation 21:6 ::