SG is the specific gravity, or the measure of gyroscopic stability applied to the bullet by spin.
Mathematically SG is the ratio of the stabilizing influences of rotating mass, vs. the de-stabilizing effects of aerodynamics. If this ratio is greater than 1.000, it means the bullet has more stabilizing influence than de-stabilizing influence, so it’s said to be stable. In practice, a bullet needs an SG of 1.5 or greater to be well stabilized, and fly with the maximum effective BC.
Read our article on Stability and BC for more information on how this can effect the BC of the bullets you shoot.
- What is the Berger Twist Rate Stability Calculator?
- How do you use a twist rate stability Calculator?
- Why would you use a twist rate calculator?
- How does the Berger twist rate calculator work?
- What is the Miller twist rate formula?
- Why is the Miller twist rule better than the Greenhill rifling formula?
- What does SG mean?
- What SG number is best?
- What SG do I want for my rifle/barrel?
- Why doesn’t the Miller twist rate formula work with flat based bullets?
- What SG do I need to stabilize a bullet?
- Why do I want an SG of 1.5 or higher?
- What does rifle twist rate mean?
- Why does barrel twist rate matter?
- What is my optimal barrel twist rate?
- What is the best barrel twist rate?
- Why is G7 BC better than G1 BC?
- What is the difference between G1 BC and G7 BC?