I have a SIG SSG-3000 which I love, have been shooting it for 5 years, fits me well, shoots like a dream, has the 24" barrel.

The twist rate is 1:11, and is spot on accurate with the 175 gr Federal Match, largely one hole

at 100 yards, and repeatable data out to 1,000 yards.

SIG also made a short production run of the same rifle in the 18" barrel, but keep the twist

rate the same, 1:11 (also seen it given as 1:12), despite a nearly 25% reduction in barrel length.

I've noted that my accuracy on that barrel is considerably looser than

the 24" barrel. I've tried the 168 gr and 175 gr, seems to be about the same.

I've tired this on and off over the last year, to be sure it wasn't just a perception

thing, and it's not, the groups are noticeably "looser" and become more so at distance,

from what I assume to the subtending angle flight path.

Now, I understand that the propose of the rifling twist is to impart gyroscopic stability to the

round when it leaves the barrel, so it seems to me the 24" barrel has more "time" to act on

the round than the 18" barrel.

Question 1:

So my questions relates to twist rate, is there a formula or standard for twist rate

based on the variables of barrel length, and bullet weight?

If so, I'm assuming that the short barrels would need a "faster" twist rate to stabilize

the round, given that it has a shorter time in the barrel.

Question 2:

I see that Benchmark Barrels offers SSG barrels, they seem like good folks, have purchased

the factory mags for the SSG from them.

Is there another barrel manufacturer for the SSG?

If I were to spec a replacement 18" barrel, what would be the ideal twist rate for the 168 gr

projectile?

I've also considered going with an 16" barrel, at the cost of muzzle velocity, to make the rifle

easier to carry with me. Thoughts on this?

Thank you!