Any gains to a gain twist?

[Dragoon300]

I had Bartlien do two gain twist barrels for me.
As was stated above they suggested no more than 1" gain. However, they do make .224 barrels with more gain for service rifle match shooting.
And there are many match shooters that use gain twist barrels, most under 1" gain. This is done to continuously improve the seal of the projectile to the rifling.
The 20mm x 103 Vulcan cannons are a serious gain twist, they start out straight and progress to a cork screw at the muzzle. This was done to get the heavy projectile rotating without stripping the rotating band off.

I decided that gain twist makes sense for my application, I wanted to get heavy bullets started with less pressure, I also had them done with 5R profile rifling which has also been said reduce friction and pressure. Along with these I had them do lefthand twist to help mitigate coriolis effect in the Northern hemisphere.
So my 6.5 PRC has a 31" 5R Lefthand 1:8.5 to 1:7.5 gain twist barrel that gives me 3311 fps average velocity with 156 grain Bergers and shoots 1/4 moa.
My 338 LM is also a 31" 5R Lefthand with 1:10.35 to 1:9.35 gain twist. I am still in load development with this, but it shoots well and is getting good velocity.
I firmly believe gain twist and 5R rifling helps get heavier bullets rotating easier, I have gotten great velocities without dangerous pressure signs running max loads. Certainly some of this is my 31" barrel length, but I seat the bullets .010 off the lands so it's not due to a lot of free bore.
Then the continuously improved sealing all the way to the muzzle, and lefthand twist can't hurt so why not use it? I have not seen anything wrong with my gain twist barrels, they shoot very accurately. I'm very happy!

 

[Mike D Texas]

I had Bartlien do two gain twist barrels for me.
As was stated above they suggested no more than 1" gain. However, they do make .224 barrels with more gain for service rifle match shooting.
And there are many match shooters that use gain twist barrels, most under 1" gain. This is done to continuously improve the seal of the projectile to the rifling.
The 20mm x 103 Vulcan cannons are a serious gain twist, they start out straight and progress to a cork screw at the muzzle. This was done to get the heavy projectile rotating without stripping the rotating band off.

I decided that gain twist makes sense for my application, I wanted to get heavy bullets started with less pressure, I also had them done with 5R profile rifling which has also been said reduce friction and pressure. Along with these I had them do lefthand twist to help mitigate coriolis effect in the Northern hemisphere.
So my 6.5 PRC has a 31" 5R Lefthand 1:8.5 to 1:7.5 gain twist barrel that gives me 3311 fps average velocity with 156 grain Bergers and shoots 1/4 moa.
My 338 LM is also a 31" 5R Lefthand with 1:10.35 to 1:9.35 gain twist. I am still in load development with this, but it shoots well and is getting good velocity.
I firmly believe gain twist and 5R rifling helps get heavier bullets rotating easier, I have gotten great velocities without dangerous pressure signs running max loads. Certainly some of this is my 31" barrel length, but I seat the bullets .010 off the lands so it's not due to a lot of free bore.
Then the continuously improved sealing all the way to the muzzle, and lefthand twist can't hurt so why not use it? I have not seen anything wrong with my gain twist barrels, they shoot very accurately. I'm very happy!

So how would a gain twist create a better seal?

 

[Dragoon300]

So how would a gain twist create a better seal?

It is continuously engraving the rifling (changing pitch) all the way to the muzzle.

 

[Ranger0]

gain twist barrel is okay for me .

 

[Beluebow]

From Bartlein.........

"What are the benefits of the gain twist type rifling?

I'll quote what Pope (Pope was one of the greatest barrel makers from a bygone era. His barrels along with Schalk who he learned from and gives credit to and Schoyen, and Zischang made barrels for the Schutzenfest type of guns/shooting in the late 1800's to early 1900's) said around a 100 years ago first. "The advantages of the gain twists are three. 1st The twist being less at the breech, gives less friction to the bullet; it therefore starts easier and quicker, giving the powder less time to burn on in front of the chamber, which therefore fouls less than in a barrel of uniform twist at the same necessary muzzle pitch (twist). 2nd The slight change in angle of the rifling, in connection with choke bore (lapping choke bore of the barrel), effectually shuts off any gas escape of gas and prevents gas cutting, which is another case of imperfect delivery. 3rd It holds a muzzle loaded bullet in position much better than a uniform twist…



Now I will add some more to this. First off I feel this applies more to a lead bullet shooter than a jacketed bullet shooter but some of the why's and why not's do overlap. With a gain twist barrel the bullet cannot go to sleep. The rifling is always putting a fresh bite on the bullet as it goes down the bore of the barrel. This is why I always go back to a cut barrel being better than a button barrel. A cut barrel even with a straight twist is more uniform and consistent than a button barrel. With button rifling the button can hit a hard spot/soft spot in the steel and it will slow the button down. The button could speed back up and do the twist it's suppose to be doing but either way you end up with a non uniform twist and it the twist keeps getting slower towards the muzzle. These two things are a accuracy killers and lead to consistency problems/fliers etc… I feel even a slight gain twist will help accuracy wise and not hurt a jacketed bullet shooter as well. For the most part I would say there is no velocity gain in a gain twist barrel with the same load. What has been conveyed to us and it goes back to Popes 1st point is that shooters have noticed that they can run a slightly heavier powder charge vs. a shooter with a straight twist barrel. As the bullet is starting easier into the rifling my only guess is the pressure isn't spiking as fast or is delaying the pressure curve. Hence forth they can get more velocity out of the gain twist barrel. I feel pressure is pressure and that the twist doesn't have anything to do with pressure for the most part but my only guess is that the gain twist like I said earlier is delaying the pressure curve. So you don't see problems as early like hard bolt lift etc… Also it's noted that even now a days our military in some 20mm and the 30mm barrels like on the A10 Warthog ground attack aircraft have gain twist type rifling in the barrels."

 

[DUCKMAN11]

White oak has the barrel I'm looking at in stock. I'm not trying to shoot camp perry matches but I also can't stand inaccurate rifles. I also verbally laugh at guys with the Gucci guns that shoot 1.5moa. I know that the heart of an AR is the BCG and barrel. All I want to do is mag feed the heaviest bullet I can and get as much velocity as possible and shoot sub moa.

It seems like the general consensus is that gain twist barrels shoot as good as any good standard barrel but are not something to write home about. I guess I should just put a straight 7tw on it and call it good. It is after all just an AR.

 

[bamban]

Any good barrel is capable of good precision. Field accuracy is something else. Boils down to precision-accuracy discussion. The latter rest on the trigger puller.

 

[Dragoon300]

From Bartlein.........

"What are the benefits of the gain twist type rifling?

I'll quote what Pope (Pope was one of the greatest barrel makers from a bygone era. His barrels along with Schalk who he learned from and gives credit to and Schoyen, and Zischang made barrels for the Schutzenfest type of guns/shooting in the late 1800's to early 1900's) said around a 100 years ago first. "The advantages of the gain twists are three. 1st The twist being less at the breech, gives less friction to the bullet; it therefore starts easier and quicker, giving the powder less time to burn on in front of the chamber, which therefore fouls less than in a barrel of uniform twist at the same necessary muzzle pitch (twist). 2nd The slight change in angle of the rifling, in connection with choke bore (lapping choke bore of the barrel), effectually shuts off any gas escape of gas and prevents gas cutting, which is another case of imperfect delivery. 3rd It holds a muzzle loaded bullet in position much better than a uniform twist…



Now I will add some more to this. First off I feel this applies more to a lead bullet shooter than a jacketed bullet shooter but some of the why's and why not's do overlap. With a gain twist barrel the bullet cannot go to sleep. The rifling is always putting a fresh bite on the bullet as it goes down the bore of the barrel. This is why I always go back to a cut barrel being better than a button barrel. A cut barrel even with a straight twist is more uniform and consistent than a button barrel. With button rifling the button can hit a hard spot/soft spot in the steel and it will slow the button down. The button could speed back up and do the twist it's suppose to be doing but either way you end up with a non uniform twist and it the twist keeps getting slower towards the muzzle. These two things are a accuracy killers and lead to consistency problems/fliers etc… I feel even a slight gain twist will help accuracy wise and not hurt a jacketed bullet shooter as well. For the most part I would say there is no velocity gain in a gain twist barrel with the same load. What has been conveyed to us and it goes back to Popes 1st point is that shooters have noticed that they can run a slightly heavier powder charge vs. a shooter with a straight twist barrel. As the bullet is starting easier into the rifling my only guess is the pressure isn't spiking as fast or is delaying the pressure curve. Hence forth they can get more velocity out of the gain twist barrel. I feel pressure is pressure and that the twist doesn't have anything to do with pressure for the most part but my only guess is that the gain twist like I said earlier is delaying the pressure curve. So you don't see problems as early like hard bolt lift etc… Also it's noted that even now a days our military in some 20mm and the 30mm barrels like on the A10 Warthog ground attack aircraft have gain twist type rifling in the barrels."

Very good write up! Great information.
I know what I found, and I am a believer. Gain twist barrels do what Pope said so many years ago, and Bartlien makes great gain twist barrels!
I had come to this conclusion and had ordered my barrels before I read a chapter in Frank Galli's book on precision marksmanship where he prefers lefthand gain twist barrels too, for the same reasons I mentioned earlier. Thank you for your post.

 

[Dragoon300]

White oak has the barrel I'm looking at in stock. I'm not trying to shoot camp perry matches but I also can't stand inaccurate rifles. I also verbally laugh at guys with the Gucci guns that shoot 1.5moa. I know that the heart of an AR is the BCG and barrel. All I want to do is mag feed the heaviest bullet I can and get as much velocity as possible and shoot sub moa.

It seems like the general consensus is that gain twist barrels shoot as good as any good standard barrel but are not something to write home about. I guess I should just put a straight 7tw on it and call it good. It is after all just an AR.

I beg to differ with gain twist barrels being "not something to write home about" see what Frank Galli wrote in his book, he has more credibility on the subject than I, but I am sold on them!
And what the above write up that Pope said so many years ago is still very true today!
I think the barrel you were looking at would be a good choice.

 

[DUCKMAN11]

Well in today's market having an item available for purchase speaks volumes. What I meant by "not something to write home about" is that it's not leaps and bounds better than a conventional barrel. Are they 10% more accurate than a conventional barrel? Perhaps at most. In a competitive environment EVERY advantage adds up. But for a gun that will be used to ear hole hogs at under 200yds I might not see a difference.

 

[Dragoon300]

Well in today's market having an item available for purchase speaks volumes. What I meant by "not something to write home about" is that it's not leaps and bounds better than a conventional barrel. Are they 10% more accurate than a conventional barrel? Perhaps at most. In a competitive environment EVERY advantage adds up. But for a gun that will be used to ear hole hogs at under 200yds I might not see a difference.

I wanted more velocity. More velocity = more range and energy. I am very pleased that I also have good accuracy as well. The gain twist shoots as accurate as I can expect or wish for, and has allowed me to load heavier charges to get higher velocity for more range and energy. Life is good!

 

[DUCKMAN11]

I wanted more velocity. More velocity = more range and energy. I am very pleased that I also have good accuracy as well. The gain twist shoots as accurate as I can expect or wish for, and has allowed me to load heavier charges to get higher velocity for more range and energy. Life is good!

Sounds like what I'm after

 

[milo-2]

I beg to differ with gain twist barrels being "not something to write home about" see what Frank Galli wrote in his book, he has more credibility on the subject than I, but I am sold on them!
And what the above write up that Pope said so many years ago is still very true today!
I think the barrel you were looking at would be a good choice.

I have read a good portion of the pitch, left gain tw ranks right up with canned beer and sliced bread. The laws of physics don't seem to apply to left tw, and adding gain is gooder.
I have been shooting a left tw 7 saum barrel for yrs, and if the majority of your rifles are right tw, you better remember the difference if you touch a shot off at distance.
I also shoot a left gain twist 6x47 Lapua, I wait for the magic. Most left gain tw out are 6mm, small cases, being fired with relatively fast powders, so I am lost on the soft start, and the subsequent velocity gains. If all the powder is burned in a short secction of the barrel as stated, does that area become a hard carbon buildup area?
Of course, it is an accurate barrel, or it would be in the scrap pile, but so has every other 6mm barrel I have had spun up.
I also shoot a right gain 6 BRA, extremely accurate, my speed seems high, 105 hybrid at 2900, 26" barrel. Is it the gain, or just the barrel, because my charge weight is not out of order, just faster.
There are names that could sell a 20 grove barrel, as we saw around 6 yrs ago with bore rider throats, I guess gain tw has survived longer, lol