Greenhill formula and the 45 ACP

Bill Daniel

New member
For those who's curiosity can become an obsession.
I got curious if the 1:16 twist rate on my Kimber Gold Match was appropriate for the 200 gr. SWC bullets I was reloading or if I could tweek better perfomance with a different bullet length. The Greenhill formula for pistol bullets less than 1500 fps gives a calculated twist rate of 1:42
K=125 .451(125/bullet length/.451)

The velocity formula K=.05
(.05*FPS*.451*.451)/bullet length in inches
gives a more workable solution.
Bill Daniel

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Prosecute criminals to the fullest extent of the law and their weapons will become harmless.
 
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