I have a ballistic stability calculation program in an Excel spreadsheet that I downloaded years ago. I can't verify the authenticity of the program but it appears to give reasonable answers.
To calculate bullet stabiilty you need to know bullet (projectile) length, bullet weight, barrel twist rate, and bullet speed. The program will then calculate whether or not the bullet will be marginally stable, fully stable, or maximally stabalized. You can call the bullet manufacturer and ask for the bullet length if you don't own a box. The length of the bullets needs to be meausured to the nearest 0.001 inches in most cases especially if you are close to one of the stability limits.
If you want I can email you a copy of the program.
Dennis