twist rate ?

[enfield]

Im just starting to pay attention to how much the twist rate effects bullet stability . I recently got a 9mm barrel liner and have made a home for it in an old Lee Enfield barrel, I chambered it to an easy to work with .357 and everything functions but when I started looking up load data I see that .357 and 38sp have a twist rate of about 1-18 and the 9mm is 1-10. why such a difference ? I would expect the 9mm would be more stable with a longer heavier bullet, would this be true ??

[Bass Ackward]

Velocity and twist rate (and ballistic coefficient) interact to produce stabilization. The more velocity a platform is capable producing the less twist "should be" be necessary.

Remember the old 244 Remington with 12 twist story with not stabilizing 100 grain bullets? Then Remington changed it to 10 twist and called it the 6MM Remington. That makes the assumption that a 12 twist won't stabilize a 100 grain bullet. But if you add case capacity like with a 240 Gibbs that can increase velocity by 600 fps, then a 12 twist works beautifully.

BC plays a big part also. The less aerodynamic something is, the faster you have to spin it to get distance. So a short stubby bullet can be more difficult to stabilize.

For 38 Specials shooting wadcutters, the twist people are migrating to is a 10 twist for 50 yard work. And most factory twist rates are set up for commonly accepted bullet weights at the full velocity potential of a cartridge. (From years ago) Which is why hard and on the top is generally the easiest way to get accuracy. If you slow down, then load balance becomes so much more important to launch it well. Another way to say this is that the faster the twist rate, the less operator error enters the picture.

The most accurate rifle I ever had for long range was a 244 Rem with 100 grainers. But only one load.

But we spin things to travel THROUGH things too. People usually only think of stabilization through air for accuracy. But stabilization through penetration will allow for deeper penetration as well. A cartridge that shoots a light bullet made need the most out of penetration to get the job done. So it is a complicated equation. Let us know if you figure it all out.

[44man]

Good show Bass!
Funny you mention the .244, it was a great caliber, far better then the .243 but came out as a varmint rifle to start. Everyone wanted a deer rifle and the media just got down on the .244. Even changing the twist did no good, gun rags ruined it at the start.
They didn't do the great .280 any favors either.
Strange they didn't also destroy the 7mm Rem mag with their pens.
One of a million reasons I tell everyone to stop reading and believing gun rags. A simple stroke of a pen can stick wrong ideas in a mans brain and lock it up.
An open mind and your own testing works. Never believe all you read.
Twist is fairly easy to work with if everything is tested but the guy that buys one bullet/boolit or mold and tries to find the lowest or highest velocity will fail and then pass the word that the gun is no good.
Like you, I contend too slow a twist in too small a case will not let you achieve enough velocity for stability. Think 1 in 38" in the Marlin .44. Even the .444 could not do it and they changed to 1 in 20" but still expect the little .44 mag to shoot. Marlin used Greenhill! [smilie=b:
I prefer a tad faster twist because velocity can always be reduced.
What really burned me up is Marlins warranty is too short to get anything fixed free.

[runfiverun]

which 9mm are you looking at.
my 358 has a 1-12.
generally the longer bullets have a faster twist designated to them.
like the 223, it started out with 1-12 [great for 45-50 gr bullets] then went to progressively faster twist rates for the heavier longer bullets.
they offer up to 1-7 now.
44 likes the faster twists in his revolvers.
i look for a slower twist in the rifles so i can shoot the higher velocities with cast.
jacketed don't seem to care much untill you get under spun, like in the above examples.

[enfield]

my 9mm liner is listed as having 1-10 twist. and when I look up data in the lyman book, 9mm is 1-10 and 38, 357 are 1-18. so in theory I should be able to shoot a long heavey boolit , correct ?

[Bass Ackward]

my 9mm liner is listed as having 1-10 twist. and when I look up data in the lyman book, 9mm is 1-10 and 38, 357 are 1-18. so in theory I should be able to shoot a long heavey boolit , correct ?


Correct. A 10 twist 357 should give you flexibility.

[StarMetal]

Good show Bass!
Funny you mention the .244, it was a great caliber, far better then the .243 but came out as a varmint rifle to start. Everyone wanted a deer rifle and the media just got down on the .244. Even changing the twist did no good, gun rags ruined it at the start.
They didn't do the great .280 any favors either.
Strange they didn't also destroy the 7mm Rem mag with their pens.
One of a million reasons I tell everyone to stop reading and believing gun rags. A simple stroke of a pen can stick wrong ideas in a mans brain and lock it up.
An open mind and your own testing works. Never believe all you read.
Twist is fairly easy to work with if everything is tested but the guy that buys one bullet/boolit or mold and tries to find the lowest or highest velocity will fail and then pass the word that the gun is no good.
Like you, I contend too slow a twist in too small a case will not let you achieve enough velocity for stability. Think 1 in 38" in the Marlin .44. Even the .444 could not do it and they changed to 1 in 20" but still expect the little .44 mag to shoot. Marlin used Greenhill! [smilie=b:
I prefer a tad faster twist because velocity can always be reduced.
What really burned me up is Marlins warranty is too short to get anything fixed free.

Jim,

I won't talk about twist to only say the 244 wouldn't handle the longer heavier bullets, but I argue about the differences between the 243 and Remingtons round. The 243 is a very good cartrdige. The 6mm Rem only beats it by a few fps hardy worth it. Another thing I don't like that Remington done was put that round on a short action. My neighbor down the mountain from me has a Remington and I load for him. It's crazy how deep I have to seat the 100 grains bullets in order to fit his Remington's receiver window. Yes you read that right. The chamber has enough freebore to seat them out, but if you do that and then try to extract a loaded cartridge you have to pull the bolt to get it out of the gun.

So in your opinion what makes the Remington round so much better besides the fact you owned one?

[StarMetal]

Velocity and twist rate (and ballistic coefficient) interact to produce stabilization. The more velocity a platform is capable producing the less twist "should be" be necessary.

Remember the old 244 Remington with 12 twist story with not stabilizing 100 grain bullets? Then Remington changed it to 10 twist and called it the 6MM Remington. That makes the assumption that a 12 twist won't stabilize a 100 grain bullet. But if you add case capacity like with a 240 Gibbs that can increase velocity by 600 fps, then a 12 twist works beautifully.

BC plays a big part also. The less aerodynamic something is, the faster you have to spin it to get distance. So a short stubby bullet can be more difficult to stabilize.

For 38 Specials shooting wadcutters, the twist people are migrating to is a 10 twist for 50 yard work. And most factory twist rates are set up for commonly accepted bullet weights at the full velocity potential of a cartridge. (From years ago) Which is why hard and on the top is generally the easiest way to get accuracy. If you slow down, then load balance becomes so much more important to launch it well. Another way to say this is that the faster the twist rate, the less operator error enters the picture.

The most accurate rifle I ever had for long range was a 244 Rem with 100 grainers. But only one load.

But we spin things to travel THROUGH things too. People usually only think of stabilization through air for accuracy. But stabilization through penetration will allow for deeper penetration as well. A cartridge that shoots a light bullet made need the most out of penetration to get the job done. So it is a complicated equation. Let us know if you figure it all out.

John,

I know a Naval Ballistics Forensic Doctor who studies wounds that will disagree with you sternly on your stabilization through penetration particularly if you say that more spin more penetration.

[44man]

Jim,

I won't talk about twist to only say the 244 wouldn't handle the longer heavier bullets, but I argue about the differences between the 243 and Remingtons round. The 243 is a very good cartrdige. The 6mm Rem only beats it by a few fps hardy worth it. Another thing I don't like that Remington done was put that round on a short action. My neighbor down the mountain from me has a Remington and I load for him. It's crazy how deep I have to seat the 100 grains bullets in order to fit his Remington's receiver window. Yes you read that right. The chamber has enough freebore to seat them out, but if you do that and then try to extract a loaded cartridge you have to pull the bolt to get it out of the gun.

So in your opinion what makes the Remington round so much better besides the fact you owned one?
It was a VARMINT rifle to start with. Remington screwed up but the cartridge was still better overall then the .243.
It has been many years and I can't picture the action any more but think it WAS on the 722A action. I liked the longer neck on the .244.
In a longer or medium action it would be premier.
I have a dislike for short necks.
I loved the .222 Rem. Then the .222 mag took it to a new level. I just never fell for the .223 either.
Just personal likes and dislikes.

[StarMetal]

It was a VARMINT rifle to start with. Remington screwed up but the cartridge was still better overall then the .243.
It has been many years and I can't picture the action any more but think it WAS on the 722A action. I liked the longer neck on the .244.
In a longer or medium action it would be premier.
I have a dislike for short necks.
I loved the .222 Rem. Then the .222 mag took it to a new level. I just never fell for the .223 either.
Just personal likes and dislikes.

Nothing wrong with likes and dislikes Jim. The 240 Weatherby beats both the 243 and 6mm but has that disgusting belt. Back when Remington first came out with it it may have been on the longer actions, but later they chambered them on short ones and seated the bullets deep.

Winchester figured the round would go both ways, varmint and deer. Remington bet it wouldn't and was wrong. Funny Remington started the 244 with the 12 twist and then when they saw the error of their way they sped the twist up, but I think went too far....and went to a 9 twist. Winchester started with a 10.

[felix]

Wasn't Winchester doing the 257 Roberts at the time? As a marketing complement with their 270? Remington had neither and decided to go with a varmint rig instead. When it did not work, they went for the 280 and they renamed their 243 using a hunting bullet twist. Remington was having good success at the time with their 22s and thought they could augment with a 243. It is sad how marketing screws everything that is engineering out the window. ... felix

[303Guy]

And then we have my 1-in-16 twist hornet sabilizing a 60gr spire point bullet! It's all in the muzzle blast.

A cast boolit requires less twist than a similar weight j-word because it is more dense and has more mass near the circumference and is shorter - if it's a round nose or semi-wadcutter. Wadcutters are aerodynamically unstable and so require more twist for longer distance. The 9mm j-word has a pointy shape, requiring a faster twist. Something like that anyway.:roll:

[Bass Ackward]

John,

I know a Naval Ballistics Forensic Doctor who studies wounds that will disagree with you sternly on your stabilization through penetration particularly if you say that more spin more penetration.


Yea? So what else is new? He will have to argue with them MM boys from Europe that could have stabilized very nicely with 10 twists. But let's get it right.

Does twist rate make a bullet fly farther? No and yes. It does make a bullet fly straighter and catch less wind longer. If a slug loses velocity slower, it goes farther. Twist rate is a range adding factor the same as for penetration.

More spin, more straight line (stabilized) penetration, less resistance, less velocity loss, deeper penetration.