Twist Rates

[Merlyn]

Why is it that whenever a rifle is advertised for sale, whether new or used, all the details of calibre, weight, barrel length, stock height, etc, are proudly displayed but the twist rate, arguably the most important piece of information after calibre and barrel length, is never mentioned?
I am currently looking for a .243 Tikka in the 'new', to them, twist rate of 1 in 8. Having phoned numerous gunsmiths that were advertising .243 Tikka's, none of them knew the figure.
Strange.

 

[HonestJohn]

Twist rates have only really come into average people’s attention because of the move to non-toxic ammo. Previously it was more of interest to target shooters and those wanting particularly long/heavy target bullets to stabilise

A dealer that says they don’t know for a .243, either knows it’s not what you’re wanting (ie. Not copper friendly) but hopes yiu’ll still buy it. OR, should follow up with ‘but I will check and let you know’.

That said, if factory barrels, you can check twist rates online for most rifles yourself

 

[blacklab3042]

Why is it that whenever a rifle is advertised for sale, whether new or used, all the details of calibre, weight, barrel length, stock height, etc, are proudly displayed but the twist rate, arguably the most important piece of information after calibre and barrel length, is never mentioned?
I am currently looking for a .243 Tikka in the 'new', to them, twist rate of 1 in 8. Having phoned numerous gunsmiths that were advertising .243 Tikka's, none of them knew the figure.
Strange.

The new twist rate of 1 in 8 is the one to have in .243 if you are planning to use copper ammunition as they have issues stabilising (apparently) with 1 in 10.

I’ve found previously that a lot gun shops don’t always know what they are selling, it’s common in all products really…

 

[grandad of the woods]

Can someone explain this twist rate with copper ammo for me a little bit more

 

[r judd]

Copper bullets are long, faster twist rates are need to stabilise them (generally)
1 in 8 twist is faster than 1 in 10
1 in 10 is faster than 1 in 14
Very basic answer to your question

 

[MarinePMI]

Can someone explain this twist rate with copper ammo for me a little bit more

To expound on r Judd's post...

A copper bullet by weight, has to be longer than a bullet with a lead core, since copper is not as heavy as lead. Hence why a faster twist is required to stabilize them, since stabilization is based on length.

 

[grandad of the woods]

Copper bullets are long, faster twist rates are need to stabilise them (generally)
1 in 8 twist is faster than 1 in 10
1 in 10 is faster than 1 in 14
Very basic answer to your question

To expound on r Judd's post...

A copper bullet by weight, has to be longer than a bullet with a lead core, since copper is not as heavy as lead. Hence why a faster twist is required to stabilize them, since stabilization is based on length.

Ok thank you, one more question. Why would you pick a 1 in 8 twist ove say a 1 in 10 ?

Sorry for stupid questions

 

[Hunter 6.5]

Why is it that whenever a rifle is advertised for sale, whether new or used, all the details of calibre, weight, barrel length, stock height, etc, are proudly displayed but the twist rate, arguably the most important piece of information after calibre and barrel length, is never mentioned?
I am currently looking for a .243 Tikka in the 'new', to them, twist rate of 1 in 8. Having phoned numerous gunsmiths that were advertising .243 Tikka's, none of them knew the figure.
Strange.

Very good point, it's something that annoying me for ages. Majority of stores can't be bothered to state a barrel length, never mind the contour. Finding that information is challenging even with a some of manufacturers (particularly twist and barrel contour).

 

[Heym SR20]

The new twist rate of 1 in 8 is the one to have in .243 if you are planning to use copper ammunition as they have issues stabilising (apparently) with 1 in 10.

I’ve found previously that a lot gun shops don’t always know what they are selling, it’s common in all products really…

Yes and no, and in reality its no longer an issue.

243’s with a 1 in 10” twist have issues long 100gn plus bullets and especially so if the copper bullets. Some struggle to stabilise long pointy boat tailed traditional bullets.

In Scotland there was a legal minimum of 100gn for bigger deer.

Several months ago this was dropped to 80gn.

A 243 with a 1 in 10” twist has no issues stabilising 80, 85 or 90 gn monolithic bullets. Indeed it shoots them a lot faster than 100gn bullets and they start off with a lot more energy and maintain more energy out to well beyond what a 243 can do on deer.

An 80gn monolithic works very well and will punch through even the big red deer and kill just as well if not better than the old 100gn bullets.

So despite all the scare mongering no reason to change the old trusty 243.

However there are plenty of the 243s that will cause lots of sucking of teeth result in our deer hunter walking out with a shiny brand new 6.5 Creedmoor. Net result lots of perfectly good 243s available for not silly money.

 

[r judd]

Ok thank you, one more question. Why would you pick a 1 in 8 twist ove say a 1 in 10 ?

Sorry for stupid questions

So that longer bullets will stabilise

 

[grandad of the woods]

So that longer bullets will stabilise

So a lower twist helps longer bullets stabilise and a higher twist for lighter rounds to stabilise?

Or am I just ****ing this whole thing up haha

 

[grandad of the woods]

Aaa you know what I never knew that hahaha so my .243 Remington 710 with a 1 in 10 is better for long heavy rounds

 

[r judd]

As @MarinePMI said to get to a similar weight as a lead bullet, copper bullets have to be longer. Twist rate is all about LENGTH not weight.
Your 1in10 will be fine for 80gr copper also fine for 100gr lead

 

[grandad of the woods]

As @MarinePMI said to get to a similar weight as a lead bullet, copper bullets have to be longer. Twist rate is all about LENGTH not weight.
Your 1in10 will be fine for 80gr copper also fine for 100gr lead

Thanks m8 I was thinking about dropping the ppu 100g lead rounds to some lighter ones but this cleared some stuff up for me now really appreciate it

 

[MarinePMI]

So a lower twist helps longer bullets stabilise and a higher twist for lighter rounds to stabilise?

Or am I just ****ing this whole thing up haha

A faster twist rate stabilizes longer bullets (if there is one twist in 8", it's a faster twist than one twist in 10"). Slower twist rates for shorter bullets, since shorter bullets (especially varmint bullets) can have thinner jackets, and will spin apart if spun to quickly with a faster twist barrel. Then all you see is a grey puff about 30 yds ahead of the muzzle when you shoot. For hunting/big game ammo though, it shouldn't be an issue; they typically have heavier jackets.

There is a lot of debate as to whether you can "overstabilize" a bullet, but at some point high RPM's will exceed the jacket's ability to keep the bullet together.

 

[Heym SR20]

So a lower twist helps longer bullets stabilise and a higher twist for lighter rounds to stabilise?

Or am I just ****ing this whole thing up haha

No. to stabilise a longer bullet its needs to spin faster, so you need more rotations within the barrel, hence a faster twist rate of 1 in 8” compared to 1 in 10”.

However a faster twist barrel is harder to push the bullet through so you end up with lower velocity

A slower twist gives more velocity, and more velocity will result in faster rotation. In a slower twist barrel you can stabilise long bullets, but you need to up the velocity which can be a challenge.

It’s all a balance.

I have noticed this with 223 51gn peregrine vlr4 bullet. This is a long copper boat tail pointy bullet. At lower powder levels it would not group in 1 in 12” .223. Upped the velocity to just off pressure signs, and it shoots really well. By comparison the same weight Fox bullet which is flat based and conical tip so quite a bit shorter, shoots really well regardless of powder charge.

In my 243 1 in 10”, I tried the Peregrine Bushmaste which is a flat nosed type bullet. In 100gn its a short bullet for copper. It shoots really well.

 

[Kiwiguy]

Brian Litz from Applied Ballistics did tests on the velocity differences with fast twist rate barrels.

Using the same make of barrel chambered in .308 Win he found that a 1:8" twist barrel was only 8fps slower than a 1:12" barrel.

This gave an average of 1.33fps velocity drop per 1 inch of increased twist rate.

 

[Alpine_hunting]

I have used different calculator of stability based on bullet specs, muzzle velocity, twist rate, atmospheric conditions....

My remaining question about all that is whether these calculation should factor in the barrel length?

If my bullet is accelerated during all its travel in the barrell, everything else equal, wouldn't a bullet fired from a 20 in barrel with 1:10 TR have the same stability factor than a bullet fired from a 22 in barrel with a 1:11 TR?

Your ideas on that are welcome.

 

[Twodogs]

Boring stuff of no real relevance to day to day stalking.
Boat tailed bullets, generally, require a faster twist whereas flat bottomed bullets benefit from a slower twist. The faster any projectile spins the greater the emphasis in respect of dispersion of any bullet misalignment in the bore and bullet imbalance.

 

[Jelen]

Why is it that whenever a rifle is advertised for sale, whether new or used, all the details of calibre, weight, barrel length, stock height, etc, are proudly displayed but the twist rate, arguably the most important piece of information after calibre and barrel length, is never mentioned?
I am currently looking for a .243 Tikka in the 'new', to them, twist rate of 1 in 8. Having phoned numerous gunsmiths that were advertising .243 Tikka's, none of them knew the figure.
Strange.

I have had exactly the same experience in my search for a Tikka T3x 1 in 8 twist .223. Weeks of trawling google through every gun shop, RFD and Website with not a single one stating the twist on their sites.