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Joined: Nov 2011
Posts: 57
Campfire Greenhorn
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Campfire Greenhorn
Joined: Nov 2011
Posts: 57 |
Please educate me on understanding twist rates for a known bullet! I want to build a hunting rifle. Most likely in .30 caliber. After looking a bbl's i am completely confused on whats needed!I know there are many variables, however I am looking for a "rule of thumb" a twist rate needed to stabilize a certain length/weight bullet. If this formula/chart even exists!
Thanks In Advance!
B King
"Shoot Low Sheriff; he's ridin a shetlend"
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Joined: Feb 2004
Posts: 10,086
Campfire Outfitter
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Campfire Outfitter
Joined: Feb 2004
Posts: 10,086 |
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Joined: Oct 2002
Posts: 96,121
Campfire Oracle
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Campfire Oracle
Joined: Oct 2002
Posts: 96,121 |
Having more (faster) twist than what the calculator spits out if FAR better than having just not enough.
More, more, more twist. Most especially with hunting rifles.
"Dear Lord, save me from Your followers"
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Joined: Nov 2005
Posts: 23,083
Campfire Ranger
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Campfire Ranger
Joined: Nov 2005
Posts: 23,083 |
1-10" is the time honored twist for .30's. Unless you figure on using bullets heavier than 220gr. it'll do fine.
"You can lead a man to logic, but you cannot make him think." Joe Harz
"Always certain, often right." Keith McCafferty
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Joined: Jul 2001
Posts: 60,086
Campfire Kahuna
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Campfire Kahuna
Joined: Jul 2001
Posts: 60,086 |
The Berger formula is very good for boattail spitzers, but will indicate more twist than needed for flat-base spitzers. Also, plastic tips are so light they should be only partially counted in overall length. The Berger formula doesn't include anything about plastic tips, probably because they don't make any plastic-tipped bullets, but the similar JBM formula does: www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi
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