Is there a chart of preferred bullet weight for twist rate?
I know certain twists like certain weight bullets, and I need to sight in a new Tikka .308.
JBM also has a catalog of bullet lengths. Neither the Greenhill or Miller formula are accurate as they tend to overestimate the required twist. I believe Berger is using the Gyroscopic Stability equation for their estimate which is a more complex formulation.Berger Stability Calculator
Twist Rate Stability Calculator
Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.bergerbullets.com
JBM Stability Calculator
JBM - Calculations - Stability
www.jbmballistics.com
You'll need some measurements for the JBM calculator, but Google should provide those for you with a little searching. JBM can also account for plastic tips, which Berger does not.
The twist is a function of the overall length of the bullet. For a fixed bore diameter the weight increases the length for similar bullet geometry.twist rate needs are determined mostly by the "length" of the bullets bearing surface not necessarily the weight.