Greenhill formula for those of us that are math challenged
For determining optimum twist rate for boolits.
For velocities less than 1800 fps
150 x DČ/BL
For velocities more than 1800 fps
180 x DČ/BL
D=diameter of bullet in inches
BL=bullet length in inches
greenhill formula post#5
http://castboolits.gunloads.com/showthread.php?t=22699
RPM formula
post#6
http://castboolits.gunloads.com/showthread.php?t=25226