Barrel Twist Rate

[CptnAwesome]

I know about twist rates and what they mean as far as what weight bullets they will stabilize. But more often I'm hearing shooters talk about getting a custom barrel that starts out with X twist rate and ends with X twist rate. Like " my new barrel starts with 1:10 twist rate and ends in 1:9".
What is the purpose in this? What would be the benefit over just getting a barrel with 1:9 twist rate all the way through?
First few times I heard it I thought nothing of it. Now I'm really curious.

 

[Turkeytider]

A barrel with two twist rates?

 

[gotboostvr]

It's called "gain twist" and as far as I can tell, it dosen't really make a more accurate barrel.

 

[mavracer]

It's called a gain twist. It's supposed to deform the bullet less.

 

[lysanderxiii]

They will actually deform the bullet more, as the engraving has to shift.

Their main advantage is allowing for higher acceleration with less stress on the driving band of a projectile.

(You also cannot make the rifling with a button or cold forging, you have to cut it.)

 

[Turkeytider]

Learn something every day!!

 

[Litetrigger]

Gain twist barrels have been made and experimented with for centuries. I've had about a dozen over the years and never had one that shot better than standard fixed twist.

 

[CptnAwesome]

Thanks for the replies all. So seems like the goal is less bullet deformation. Which ( probably depending on who you talk to), it does or does not accomplish.

 

[PapaG]

Was very popular with muzzle loading rifles. Slow twist to start the balloon its way with less chance of stripping changing to a faster finish to give the ball the correct spin for its size. I built a 40 cal with gain twist way back when. It was schemed away from me before I had time to see what it would really do. Did shoot well.

 

[CapnMac]

Gain twist rifling was one of Signore Carcano's signature additions to firearms history.
It's a feature that is oft touted for accuracy that gets dropped for expediency..

Is it better? Maybe. It tends to wind up being impractical in anything other than heavily specialized weapons.

If you are paying for a custom barrel already, the additional cost is not really going to be significant if it's an offered feature. And, if it makes you happy, then, you are happy. Sounds like a win to me. Can you be happy without it? Maybe. Only you know what makes you happy.

 

[LiveLife]

Until 1000 yard match shooters and military snipers start setting new world records with "gain twist" barrels, I will keep chugging along with my "no gain twist" barrels.

 

[Jim Watson]

How do you know they are not? Bartlein is popular among target shooters and they will rifle a barrel at any rate, any gain.

 

[Nature Boy]

All it takes is for one guy to win a match with one and they become the greatest thing since (___fill in the blank__)

 

[LiveLife]

How do you know they are not? Bartlein is popular among target shooters and they will rifle a barrel at any rate, any gain.

Perhaps @Nature Boy could enlighten us but I do not recall various rimfire, benchrest, F Class, Palma match forum threads mentioning gain twist barrels. And these shooters will chase after slightest edge for accuracy.

No mention of "gain twist" barrel on Rifleman's Journal, dedicated to 1000 yard Palma match shooting - https://web.archive.org/web/2015030...ansjournal.blogspot.com/p/articles-index.html

And I know of no military sniper barrel that has gain twist.

ETA: Wow, @Nature Boy must have sensed I was typing his name ...

All it takes is for one guy to win a match with one and they become the greatest thing since (___fill in the blank__)

Question is, "Do you currently know of any match shooter using 'gain twist' barrel for competition?"

Gain twist barrels have been made and experimented with for centuries. I've had about a dozen over the years and never had one that shot better than standard fixed twist.

Perhaps that's why "gain twist" barrels are not found in long range/military sniper barrels?

 

[Riomouse911]

The only fairly popular gain-twist firearm I can think of that is factory made is the S&W 460 XVR revolver chambering the .460 S&W magnum.

No others come to mind off the top of my head.

Stay safe.

 

[lysanderxiii]

The only major advantage gain twist rifling has over constant twist rifling is lower shear stress on the engraved rifling on the projectile. This is a big issue if you are trying to launch a 1/4 pound bullet to 3,000+ fps, not so much if the bullet only weighs 200 grains or less. Testing with 20mm show a small increase in muzzle velocity, but I doubt any gains in small caliber stuff would be worth the expense and effort.

 

[Nature Boy]

Do you currently know of any match shooter using 'gain twist' barrel for competition

Personally, I don’t.

If you do a search on Accurate Shooter you’ll see a mix of those that swear by them and those that say it doesn’t have any effect on accuracy.

I think it’s one of those concepts like moly coating bullets or cryogeniclly treated barrels. People try it because it sounds plausible and it might give them an edge. Those that have success keep doing it and those that don’t abandon it.