Miller Stability Formula
Definition
A dimensionless stability factor (Sg) formulation published by Donald Miller in 2005, calibrated for modern spitzer bullets. Sg greater than or equal to 1.5 indicates adequate stability. More accurate than Greenhill for pointed high-BC projectiles.
- Author
- Donald Miller
- Published
- 2005
- Output
- Gyroscopic stability factor (Sg)
- Stability threshold
- Sg of about 1.5 or greater
- Advantage over Greenhill
- More accurate for modern spitzer bullets
Common questions
Why did the older Greenhill formula need replacing for modern bullets?+
Greenhill's rule was developed for older, blunter bullet shapes and rifling conventions of its era, and it becomes less accurate for the long, pointed spitzer bullet profiles common in modern high-velocity ammunition, where Miller's later formula gives closer agreement with observed flight stability.
What does an unstable gyroscopic factor mean for a fired bullet?+
A bullet with insufficient spin relative to its shape tends to tumble or yaw in flight instead of tracking point-first, degrading accuracy and producing an irregular, keyholed wound or impact pattern that differs from a stable, point-on strike.
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