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-   -   Barrel twist (http://www.quarterbore.net/forums/showthread.php?t=1895)

RWBlue 05-17-2008 02:05 AM

Barrel twist
 
I hate to admit this, but the more I read, the I can't get it straight in my brain.
I need a generally stable bullet to keep from having a baffle strike.
I would like to have a less than perfectly stable bullet for terminal effect?

I will be loading subsonic and supersonic ammo.
What is the ultimate bullet weight for each of these.
Or how heavy can I go?
Does bullet shape effect the twist needed to stabilize a bullet?


300 Whisper 1 in 7.5 twist barrel.

Springfield standard M1A (1 in 12 twist)

Century Arms Yugo underfolder (unknown twist and not in my hands today)

Thank you

RWBlue 05-17-2008 09:35 PM

http://members.shaw.ca/cronhelm/DevelopSubsonic.html

Computer programs that calculate projectile stability are available free on the Internet. These calculators usually quote a Stability Factor (SF) of 1.3 for full stabilization in a conventional load. It has been found through testing that a SF in the range of 2.0 to 2.2 or greater is needed for a bullet to fully stabilize at subsonic velocity. This depends on how well the bullet is balanced with its center of mass. Lapua makes a special subsonic 200 grain .30 caliber bullet that is stable with a SF of only 1.36. Bullet Stability Calculator

What do you think?


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