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Author Topic: twist calculator  (Read 841 times)

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Offline mitchell

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twist calculator
« on: December 07, 2005, 06:02:12 PM »
wasn't somebod talking about a twist calculator a while back ???? i could use one if you guys know of any out there on the web.
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Offline GrampaMike

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twist calculator
« Reply #1 on: December 08, 2005, 11:40:51 AM »
The Greenhill formula is:
Twist = 150 x ((BD x BD) / BL)
Where BD = bullet diameter in inches
BL = bullet length in inches
150 = a constant

I use a modified Greenhill Formula:
Twist = ((MV x 0.02806) + 90.79) x ((BD x BD) / BL)
Where MV = muzzle velocity
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Grampa Mike
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Offline trotterlg

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twist calculator
« Reply #2 on: December 09, 2005, 09:31:17 AM »
Try this if you have microsoft XL the spreadsheet on your machine.  Larry

http://www.22-250.com/bullet/bulletstabilitycalc.xls
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