Question regarding Berger 185gr & twist rate

[sfvshooter]

I have an HS Precision HTR 308 (24" 1:12 twist). Below is the typical group I get with Federal SMK 175gr @ 100 yards (don't reload, but 2,580 fps).



I noticed Federal Berger Juggernaut 185gr had superior ballistics and tried it out, but my groups opened up quite a bit. I went to Berger's twist rate calculator and at estimated 2550 fps (didn't chronograph), it states with the 1:12 twist, it's marginally stable.

I picked up a Remington 700 308 5R 20" 1:10 twist barreled action and an XLR chassis. I estimated 2500 fps (will take it out this weekend to break in & chronograph) and it says it's stable.

I'm somewhat new to shooting, but I would've thought 24" 1:12 and 20" 1:10 would yield similar results since both have 2 revolutions. Maybe this is a question for Sniper's Hide, but can someone educate me why there's such a disparity in stability between the two barrels?

[theLBC]

1:10 will still spin faster (unless i am not thinking clearly)

[sfvshooter]

1:10 will still spin faster (unless i am not thinking clearly)

I know faster twist rate is necessary to stabilize heavier bullets, but aside from marginal gain in velocity, what does barrel length provide?

[sigstroker]

The need for a longer rifle case.

[sfvshooter]

The need for a longer rifle case.

Great...now I understand why I have 3 Pelican 1750 cases.

[baih777]

Which Remington action are you using with the 308 5r barrel.

The stainless version rem 700 308 5r 20inch barrel has 11.25 twist.
Unless it's from a magpul Remington 700.

[sfvshooter]

Which Remington action are you using with the 308 5r barrel.

The stainless version rem 700 308 5r 20inch barrel has 11.25 twist.
Unless it's from a magpul Remington 700.

[baih777]

That must be a newer version.
Older police where 1/12 twist.

[LynnJr]

Twist rate is not dependent on barrel length or pistols wouldn't shoot well.
The longer barrel ads weight/velocity and balances the rifles differently.
There are way too many subpar posters on that other forum that mess it up as a reliable source for a new shooter in my humble opinion.

[firefly416]

I know faster twist rate is necessary to stabilize heavier bullets, but aside from marginal gain in velocity, what does barrel length provide?

Faster twist isn't necessarily for heavier bullets but more so for longer ones. Look at the solid projectile weights and the twist rates needed to stabilize them and you'll see it's not strictly about bullet weight.

A longer barrel won't give you much except more velocity. There is diminishing returns though once you get very long with the barrel.

[smoothy8500]

There are way too many subpar posters on that other forum that mess it up as a reliable source for a new shooter in my humble opinion.

Hmmmm, I don't think it's any less here...

[ar15barrels]

I have an HS Precision HTR 308 (24" 1:12 twist). Below is the typical group I get with Federal SMK 175gr @ 100 yards (don't reload, but 2,580 fps).



I noticed Federal Berger Juggernaut 185gr had superior ballistics and tried it out, but my groups opened up quite a bit. I went to Berger's twist rate calculator and at estimated 2550 fps (didn't chronograph), it states with the 1:12 twist, it's marginally stable.

I picked up a Remington 700 308 5R 20" 1:10 twist barreled action and an XLR chassis. I estimated 2500 fps (will take it out this weekend to break in & chronograph) and it says it's stable.

I'm somewhat new to shooting, but I would've thought 24" 1:12 and 20" 1:10 would yield similar results since both have 2 revolutions. Maybe this is a question for Sniper's Hide, but can someone educate me why there's such a disparity in stability between the two barrels?

The number of revolutions is not a factor.
The bullet length, velocity and spin RATE is what matters.

[LynnJr]

Hmmmm, I don't think it's any less here...

True but over there you see more subpar Experts.

[sfvshooter]

Faster twist isn't necessarily for heavier bullets but more so for longer ones. Look at the solid projectile weights and the twist rates needed to stabilize them and you'll see it's not strictly about bullet weight.

A longer barrel won't give you much except more velocity. There is diminishing returns though once you get very long with the barrel.

Hypothetically, if you have 2 bullets that are both 175gr and one is longer than the other, you'd need higher twist to stabilize the longer bullet? Learned something new today.

Looks as if Berger 185gr Juggernaut is 1.353" and SMK 175gr is 1.24"

[ar15barrels]

That must be a newer version.
Older police where 1/12 twist.

Remington makes all 20" 308 heavy barrels with a 1:10 twist regardless of which product line.
The 1:12 police 308's were 24" or 26" long barrels depending on the era.