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Precision setup

Bullet Stability Calculator

Use the Miller stability formula to see if your twist rate keeps bullets safely gyroscopically stable.

Use the projectile weight from the manufacturer, not the complete cartridge weight.
Enter the actual projectile diameter, such as 0.224, 0.264, or 0.308 inches. Do not enter the cartridge name.
Measure or use the manufacturer specification for the complete projectile from base to tip. Bullet length, not cartridge overall length, is required.
Enter the second number from the twist marking. For a 1:8 twist barrel, enter 8.
Enter average velocity from this firearm and load. Stability changes with launch velocity.
Enter ambient air temperature for the conditions being evaluated. Colder, denser air generally reduces calculated stability.
Use absolute pressure at the shooting location rather than sea-level-corrected barometric pressure.
Gyroscopic stability resultSG is the calculated gyroscopic stability factor. Values near 1.4 to 2.0 are generally a useful target; values below 1.0 indicate likely instability.
Enter your data to see the stability factor.