Twist rate!

[Albifrons]

I’m considering exchanging my .243 for a .308 and was chatting to a few friends about what gun etc to get.
Then twist rates entered the discussion which has completely fried my mind.

Ive searched through the threads about twist rates in .308 calibre and cannot find a definitive answer, so my question is what’s the ideal twist rate in .308, shooting something like factory 140-170 grain in both lead and lead free loads.

Thanks in advance.

 

[markyw]

I think most rifles are a 1:10 now days, but older rifles may be 1:12 or 1:11. Faster twist can stabilise heavier bullets, but can also over stabilise lighter bullets.
What range will you be shooting at, as for under 500yds the standard twist rates will be fine with bullets up to 175gr and maybe a little heavier.

Regards

 

[Albifrons]

I think most rifles are a 1:10 now days, but older rifles may be 1:12 or 1:11. Faster twist can stabilise heavier bullets, but can also over stabilise lighter bullets.
What range will you be shooting at, as for under 500yds the standard twist rates will be fine with bullets up to 175gr and maybe a little heavier.

Regards

Will be shooting out only to 150 yds and perhaps a little more at deer, but this convo today has really muddied the water, so I think anything between 1-10 and 1-12 will be fine…I hope.

 

[M@tt]

Over stabilising doesn't matter, it's either stable or not, and I doubt you'd be able push the bullets fast enough to get them to spin apart, especially without reloading outside the envelope.

Go with the fastest twist you can find in your chosen off the shelf make/model and you'll be fine.

 

[SimpleSimon]

Note that faster twist rates are for stabilising longer bullets, not necessarily heavier ones. A copper (or other non-lead bullet) of the same weight will be longer than a lead-cored bullet due to the lower density of copper. Some bullets are also designed long regardless of material.

 

[kieran222]

I’m considering exchanging my .243 for a .308 and was chatting to a few friends about what gun etc to get.
Then twist rates entered the discussion which has completely fried my mind.

Ive searched through the threads about twist rates in .308 calibre and cannot find a definitive answer, so my question is what’s the ideal twist rate in .308, shooting something like factory 140-170 grain in both lead and lead free loads.

Thanks in advance.

Forget you ever had that conversation. It will not effect you for what you have said that you will be using it for. The twist rate doesn't just relate to 308, you probably don't know what the twist rate of your 243 was and I assume that you haven't had any issues with that.

 

[markyw]

Overstabilisation can matter as it causes yaw (something along the lines of the bullet's rotational axis does not allow it to cleanly follow the trajectory), but at around 150yds this will likely not matter. Not so much about spinning apart, more about tumbling. Agree with the point on fastest twist though, covers all bases.

As for longer bullets vs heavier bullets where twist rate is concerned, they tend to be related (with some exceptions). I have not taken copper into account as do not shoot it, but a 200gr SMK (35.4mm) is longer than a 175gr SMK (32.2mm), which in turn is longer than a 155gr SMK (28.8mm).

Regards

Mark

 

[Malxwal]

If you kind of define the shooting you need/want to do with it ? Your choice of copper bullet will determine the minimum twist you need. But as an example, I have a friend contracting who runs two standard T3x Super Varmint 308s and readily available factory copper ammo with great success.

 

[Demetrius]

I used 1:11 twist 30" barrels with 155 grain Lapua Scenar's......... and very good results up to 1000yds....

D.

 

[Twodogs]

My 1:12 Anschutz stabilises everything I’ve tried from 175 grain lead to the 30 cal YewTree coppers, though only used at stalking ranges.
YewTree make no special recommendations for twist rate for the 30 cal bullets, they do for other calibres.

 

[The Grouse]

Finding the right ammo for the rifle will make more of a impact than the twist. Both my 1/10 and 1/12 twist .308 rifles love 150gr sako blades, one ragged hole group at 100m but Hornady, Geco, Norma etc not even close.

 

[palo]

My sako trg and tikka 308 were 1/11 twist and i used bullets from 150 to 168 with great results.
I think the new sako and tikka rifles are 1/10 now. Probably because of the use of copper bullets.
1/10 or 1/11 will be fine

 

[andyk]

I’ve never really heard much talk of twist rate for 308.

In reality it’s rare for it to be used with >180gr bullets, which aren’t even that heavy for a 30 cal, so I expect it’s a case where you’re unlikely to want to use the sorts of bullets where you’d need to worry.

It’s a bit different with, say, 243 where even the ‘standard’ 100gr can be at the limit of stability, so anything of that weight and sleek becomes a problem.

 

[TimWest308]

I think all standard 308 tikkas are 1 in 11”

 

[Ginc]

Go for 1:10 ! Really god for cooper bullets and lead cored ones with weight 150gr+ ! 1:12 is less forgiving with monometallic, not worth the hassle.

 

[tackb]

When I rebarrelled my 308 I went for 1-10 as the best compromise and it enables me to shoot 190-220gr subs as well

 

[Nimrod1960]

Good post
I am also adding a 308 to the cabinet and getting my knickers in a knot re twist rates and non lead.
Reading responses with interest. SD at its best.

 

[alberta boy]

A standard 1 in 10 twist will do anything you need , and a 1 in 12 wouldn't bother me either . I've used both with a broad range of bullets weights and ballistic coefficients , never had a problem .
AB

 

[Ginc]

A standard 1 in 10 twist will do anything you need , and a 1 in 12 wouldn't bother me either . I've used both with a broad range of bullets weights and ballistic coefficients , never had a problem .
AB

1:12 struggle with long, high BC bullets. Like 178gr Eld-X. And gives marginal success with 168gr Barnes -ttsx.

 

[Albifrons]

Good post
I am also adding a 308 to the cabinet and getting my knickers in a knot re twist rates and non lead.
Reading responses with interest. SD at its best.

Yes, really is a wealth of knowledge and experience on this platform.