Range Report Sg Numbers how high?

[Eric32]

Hello,

I was wanting to do a short barrel 308win and looking for info on how high of a SG number can I go before it goes to shit? I was thinking 3.5 was the point but I would like to hear some real world numbers and experiences.

 

[308pirate]

What's an Sg number? Not familiar with that term.

 

[Fig]

Air Force code?

 

[Eric32]

http://www.bergerbullets.com/twist-rate-calculator/


Here you go, its a number based on spin for stability

 

[Fig]

Most just call that “Twist”. It doesn’t depend on barrel length. It depends on the bullet.

 

[Fig]

It’s on the chart anything above 1.5 is completely stable. You gain nothing by going higher, but that’s just a guide. Reality doesn’t perfectly follow the equation.

 

[Eric32]

I understand that, i am asking on experiences beyond the normal SG of 1.5, looking into 3.5+ and any effect it has on long range performance.

 

[Fig]

What’s “Long Range”? 500yds? 1000 yds? 1 mi?

Again, it entirely depends on the bullet/velocity. I’d say under 1000 yds Berger’s calculator is spot on, and once you are stable (1.5+) you don’t gain anything by going higher. That doesn’t hold for ELR, hyper stabilized bullets, or unusual velocities. For .308 under a normal, book charge you’re good to go with 1.5.

 

[Fig]

1:12 should be good. I wouldn’t go
More than 1:10 unless you’re shooting depleted uranium.

 

[Eric32]

Thanks for your input