Quote:
Originally Posted by fltbed
Most firearm manufactures use the old Greenhill formula to determine twist rate. It’s a mathematical formula taking into account the bore diameter, bullet length and velocity to come up with an “ideal” twist rate. You can use this formula for almost any caliber from 17 caliber to artillery and you’ll find that whatever twist rate comes up, that’s pretty close to what all the manufactures have been making for years.
Jeff
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Very true except the Greenhill formula was developed during a time when state of the art projectiles were lead and round nosed. It doesn't work very well with boat-tailed match bullets and falls apart with with VLD projectiles. It fails completely with mono-metal bullets like the Barnes.
However, since we're talking about pistol bullets, it works well enough.