Gain Twist Barrels?

[danny]

Has anyone used gain twist barrels that can relate any experiences? I am not really looking to use gain twist, but a builder I think I might use does, and likes them. Sometimes you should use the parts a builder has selected and feels comfortable with and has had success.

Danny

 

[Kurz]

A few of us have been using gain twist barrels for about 20 years or so. The first ones had a greater range of twist as compared to the current ideal of 1" of change or less. Originally we were getting 1:14" to 1:8" for 6mm barrels. We didn't notice any extravagant changes in accuracy then or now, sometimes it was worse... But it's a variable that folks like to experiment with so it continues to be offered. The big bore government contracts for 20mm and above still concentrate on using gain twist.

Here is an article to add to your base information:

http://bulletin.accurateshooter.com/2008/08/boyer-succeeds-with-bartlein-gain-twist-barrel/

Regards.

 

[Sniper338]

Yeah everything ive read when this topic comes up is no one can tell a difference

 

[Kurz]

I think the potential for change in accuracy comes with the amount of engraving which occurs on the bullet jacket. There is slightly more surface area engraved by gain twist as opposed to the standard single rate twist. There is the potential for discussion concerning the aerodynamics of the bullet because of the stated engraving. But there needs to be a separation of discussion regarding standard cup and core bullets as opposed to the new generation of solids with driving bands in the long range shooting competitions.

Regards.

 

[Geno C]

A couple guys I shoot with use them and report being about to squeeze more velocity out of a gain twist. I would say that's hard to quantify since no 2 barrels are the same.

 

[LHSmith]

I would say that's hard to quantify since no 2 barrels are the same.

Yes.....a sad fact that many who visit here have difficulty embracing.

 

[dickn52]

I use them in Rimfire, and the two I have are absolutely better than the originals.

 

[Geno C]

I use them in Rimfire, and the two I have are absolutely better than the originals.

But if the originals were that good you might not have replaced them

 

[strut64]

I have done some thinking about this issue and have 2 issues with the notion of gain twist barrels. If the rate of twist of the barrel changes, the bullet must be re-engraving itself to match the change all along the passage through the barrel. Also, In a barrel with fixed rate of twist, The bullet upon firing starts at zero upon ignition and reaches full velocity at exit so the rate of rotation must be accelorating all along the path from chamber to muzzle. So I am having r=trouble seeing any benifit of gain twist in my mind.

 

[USMCDOC]

Strut,

How do you figure that the bullet is "re-engraving" itself?

 

[Eddie Harren]

Better'n the funny papers!

 

[Liven The Dream]

Friend testing a .223 Palma Barrel Gain Twist 1-13 to 1-7 More Velocity than a Standard 1-7 or 1-7.7 with 90gr. Berger's.

At this point not that sure of the Accuracy compared to a .308 ??

 

[clowdis]

I've used gain twist Palma barrels that shot well but no better than straight twist barrels. Gain was developed to slowly accelerate the spin on lead bullets to keep them from stripping the rifling. Harry Pope did some research with gain twist barrels back in the 1800's but as far as I know he never settled on them as being better than a straight twist for match shooting.

 

[M14AMU]

A 'hangover' from blackpowder days!!

 

[Alex Wheeler]

I like gain twists. But I prefer a slight gain, 1/4 to 1/2" The faster the twist of a barrel the less area the bore has because there is more land in the cross section. What a gain twist does in ensure the is some choke. We know barrels that loosen up at the muzzle dont perform as well. A slight gain help prevent this. I do not believe they would shoot better than a properly machined and lapped non-gain twist. All rock creeks have a slight gain, even though its not advertised. They are one of the best shooting barrel out there, I have been using more of them than any other at this point.

 

[IdahoSharpshooter]

I have two gain twist barrels from Bartlein, and one or two more on order.

One of the good things about them, is that you can do some measuring on a bullet, and see the exact twist it would require for an SG of 1.75 or so. Then order a gain twist barrel to start 1/2" slower, and end at 1/2" faster if you choose

I would expect Tony Boyer did not switch barrel makers and dimensions on a whim...

 

[M-61]

I have done some thinking about this issue and have 2 issues with the notion of gain twist barrels. If the rate of twist of the barrel changes, the bullet must be re-engraving itself to match the change all along the passage through the barrel. Also, In a barrel with fixed rate of twist, The bullet upon firing starts at zero upon ignition and reaches full velocity at exit so the rate of rotation must be accelorating all along the path from chamber to muzzle. So I am having r=trouble seeing any benifit of gain twist in my mind.

Lost me here: How is the bullet "RE-ENGRAVING" itself? If it's say a 5 groove barrel regardless of twist rate OR GAIN twist it is exiting as a bullet with 5 rifling marks on it.

 

[M-61]

This might be totally wrong but my thoughts on gain twist (I like the idea) maybe the reason the military uses it in anything from 20mm and up MAY have to do with torque. I would think that a gradual gain in twist would produce less torquing of the barrel. Instead of slamming the bullet right up to the full twist a it is fired, it may happen with a more gentle torque. When you are into 20 & 30mm size bullets size (weight) this (if it exists) would become more pronounced. I have NO idea if the above happens in reality nor what effect it is on much smaller projectiles. I have been told gain twist barrels are more difficult to produce which usually means more money. I am sure a barrel maker would know what is involved.
Holland & Holland made a paradox barrel years ago in which the rifling did not start until ½ way down the tube, there's lots of different ways to look at this.

 

[JDMock]

I have shot 2 different gain twist barrels. One is a 6 PPC and the other is a 6 Dasher. I will be shooting the Dasher in a 600 yard match Saturday. It has won many trophies for me and has over 2500 rounds and still shoots great. It has a 8.25 to 7.75 twist. Two of the best short range shooters on this planet use gain twist barrels. One is Gene Bukys and the other is Tony Boyer (look up their accomplishments if you doubt me). The gain twist Bartleins may not work well in theory, but they sure do well on the target. Good shooting....James

 

[FrankG]

I can write a book on this stuff but where do I start!

We've done twist starting at zero and ending at the twist rate the customer wanted. So we can basically do anything you want and not just make a slight gain like a 0.25 of a twist gain etc...

Some more examples.....14 to 7 twist, 28 to 20, 0 to 13.5, 13.85 to 13.75, 11 to 10, 13 to 6.5 etc....

We do have a ammunition pressure test barrel being tested at a ammo maker right now. It goes from 12 to 8 twist. When I get the final results back I will be posting it first on SH as that's where it all started. Will have good hard data to go off of in regards to pressures and velocities vs. a straight barrel in the same caliber so it's apples and apples for comparison. The only difference was the twist rates.

Joe Carlos for all of his high end AR match rifles is buying mostly GT barrels to help fight bullet failure with the 90gr. bullets and trying to get all the velocity he can out of them etc...go to our testimonial page (it's all new and still adding stuff) but Greg's rifle built by Joe and Derek's rifle all have GT barrels on them.

http://bartleinbarrels.com/testimonials/

Also go to our FAQ page and I do address some of this as well but it needs to be updated as more information is received.

http://bartleinbarrels.com/barrel-faq/

Later, Frank
Bartlein Barrels