Bartlein Barrels introduces Carbon Fiber barrels!

[Hohn]

Carbon fiber has a very strong vibration dampening effect. I would think a CF wrapped barrel of equal weight will have superior vibration dampening to an unwrapped barrel of equal weight.

ON the contrary, carbon fiber actually resonates very well, which is why it is used to make cellos and violins and guitars. It has a very high Q value, but it varies with weave and fiber orientation and such.

 

[Ned Ludd]

The considerations of barrel flex/stiffness, weight, and the appropriate contour can be addressed relatively easily. I'm much more concerned about heat. Typical carbon fiber composites fall in the range of about 10-fold less efficient conductors of thermal energy than steel of comparable mass/thickness. When combined with the fact that the steel sleeve inside the carbon fiber has less mass than a steel barrel of comparable overall contour, my concern is that it would effectively be all that different from insulating a pencil thin steel barrel. For some types of shooting, this wouldn't be much of a consideration. However, for disciplines that routinely use long strings of fire, it may not be desirable.

Has anything been done to improve the thermal conductivity of the carbon fiber wrap? How will a carbon fiber-wrapped barrel heat up relative to a steel barrel of comparable overall contour over long strings of fire?

 

[FrankG]

I have to ask, is this move because you have determined there is an advantage to carbon fiber barrels, or is this primarily driven by market demands?

This is the 3rd go around in working with cfw barrels. The ones we made before and in testing competitors barrels we never got the warm and fuzzy about them.

That being said we we’re asked by one of our top customers to please take a look at doing them again. This was being driven for the hunting rifle crowd and our customer didn’t want to use other cfw barrels. So we worked on it again and doing it differently and got the best results we’ve ever seen. So with that being said we decided to offer the cfw barrels to the market.

Advantage? The question I will ask or should I say you should ask...what are you building the gun for?

I don’t see an advantage off hand per say. The wrap we are using does wick the heat faster from the barrel. Other types we’ve worked with didn’t seem to do that. That being said will it help barrel life? I’ll say little if any. Keep in mind rate of fire, what the barrel is chambered in, the load being shot thru it etc...I feel has a bigger impact. Think of this.....every-time you pull the trigger the temperature in the throat area of the chamber if I recall correctly on the low end is around 2200F. That’s the temperature of lava. So every time you pull the trigger you have a nice little flame thrower effect going on.

The customers/shops that where involved in the testing like GA Precision, Stuteville and SPR....all gave us excellent feedback. I’ll quote one of them, “They see no difference in performance between our cfw barrels and our steel barrels.”

Kind of like fluting a barrel? Is there a difference between a fluted and unfluted barrel in terms of performance? I say no. I would not ever flute a button rifled or hammer forged barrel but other than that fluting doesn’t really do anything for you except takes weight out of the gun and it looks cool. I kind of look at the cfw the same way. So for a different / cool type lighter weight hunting rifle? Sure. I can also change the contour of a regular steel barrel and achieve the same thing as well.

Am I putting one together for myself? Yes. Why? Because I want one. My barrel will be the green colored cfw. Will I use it for like F Class? At this time I’ll say no. I want weight in the gun. Can’t get that with cfw barrel.

Later, Frank
Bartlein Barrels

 

[FrankG]

The considerations of barrel flex/stiffness, weight, and the appropriate contour can be addressed relatively easily. I'm much more concerned about heat. Typical carbon fiber composites fall in the range of about 10-fold less efficient conductors of thermal energy than steel of comparable mass/thickness. When combined with the fact that the steel sleeve inside the carbon fiber has less mass than a steel barrel of comparable overall contour, my concern is that it would effectively be all that different from insulating a pencil thin steel barrel. For some types of shooting, this wouldn't be much of a consideration. However, for disciplines that routinely use long strings of fire, it may not be desirable.

Has anything been done to improve the thermal conductivity of the carbon fiber wrap? How will a carbon fiber-wrapped barrel heat up relative to a steel barrel of comparable overall contour over long strings of fire?

There are different types of carbon fiber being used on barrels. Some insulate and some wick the heat. So yes I agree with you. From the cfw barrels we tested in the past I would say it is a insulater more than anything else. Now I will say I do believe it can be different.

The wrap that is being done to ours I’ll tell you will wick the heat better. Jeff and I where doing some testing/shooting back in Feb at the range. Temp was 17F outside. After about the first 10 shots thru the guns (6.5cm and 308win) and I went to shoot another couple 5 shot groups that after 7 rounds I had so much mirage coming off the barrel that the scopes crosshair was using the whole 1” paster at a 100 yards. I had to let the gun sit for a few minutes and then went to 3 shot groups. Next time to the range I put my F class rifles mirage shield on the barrel so I didn’t have to deal with that.

 

[FrankG]

Weight has its own effect on accuracy because it relates to how recoil forces hit the action and deflect it. All else being equal, a heavier barrel deflects the action less and transmits less vibration. See "rifle accuracy facts" book for details.

Also a heavier gun over a long period of firing the shooter takes less of a beating per say and over a long period of time this usually helps the shooter shoot better as well.

Just talking steel barrels also I would tell you the contour of the barrel isn’t as critical as some think it is. I’ve shot plenty of Palma type contours that shot as good or better than say a heavy varmint type contour.

Yes also a heavier contour barrel that has a lot of stress in the blank or a bad bow to it as it heats up will resist the barrel wondering and effecting the accuracy. I feel this is more common in a button barrel than a cut rifled barrel because of stress being induced into the blank during button rifling. Residual stress in the blank is one thing that no barrel maker can measure for in my opinion.

 

[FrankG]

Con: It's going to cost you a lot more if you screw up chambering, LOL

You got that right!

 

[FrankG]

Is there a weight chart for the barrels so we can see the weight advantages ? Possibly a contour chart also ?

I’ll post one on Monday when I get back to work.

 

[Hohn]

Residual stress in the blank is one thing that no barrel maker can measure for in my opinion.

There are ways to measure residual stress (we do it at work in our major castings) but to my knowledge all of them involve destroying the part.

 

[rwj]

Reduced weight seems to be the primary factor which certainly makes sense for hunting rifles! Would competition shooters in disciplines having weight limits realize an advantage if the reduced barrel weight could be used in other areas - like larger/heavier optics?

 

[284winner]

Good news as I haven't decided which carbon barrel I want for my next rifle. Gives me another option. Weight is the biggest factor.

 

[FrankG]

There are ways to measure residual stress (we do it at work in our major castings) but to my knowledge all of them involve destroying the part.

That’s the problem. The part gets destroyed. How do you make a barrel and anywhere during the process test it with out destroying it?

 

[FrankG]

Reduced weight seems to be the primary factor which certainly makes sense for hunting rifles! Would competition shooters in disciplines having weight limits realize an advantage if the reduced barrel weight could be used in other areas - like larger/heavier optics?

I’ll give you a weird one....in PRS it started out heavy barrels....then the trend was going lighter like Palma contours, cfw wrapped etc...and then you virtually didn’t see any cfw barrels period and the trend again was back to heavier. Guys want less recoil and to be able to see the trace of the bullet to the target.

GA Precision got they’re first order of cfw barrels from us and when we all went public with it....he sold out of all of his 6mm and 6.5mm PRS type barrels in like a day and half. None of us could’ve predicted that. So are shooters been looking for a quality cfw barrel to go back to in PRS? Are we seeing the tip of the iceberg? Almost impossible to predict.

It is possible they could see an advantage on a weight savings in the barrel and put the weight else where they need it like you said. Optics, stocks etc....but I would caution that you want the gun balanced still weight wise.

 

[rwj]

That’s the problem. The part gets destroyed. How do you make a barrel and anywhere during the process test it with out destroying it?

The best non-destructive approach is process control of the material during manufacturing... which I suspect Bartlein already has in place!

 

[Straightshooter1]

There are different types of carbon fiber being used on barrels. Some insulate and some wick the heat. So yes I agree with you. From the cfw barrels we tested in the past I would say it is a insulater more than anything else. Now I will say I do believe it can be different.

The wrap that is being done to ours I’ll tell you will wick the heat better. Jeff and I where doing some testing/shooting back in Feb at the range. Temp was 17F outside. After about the first 10 shots thru the guns (6.5cm and 308win) and I went to shoot another couple 5 shot groups that after 7 rounds I had so much mirage coming off the barrel that the scopes crosshair was using the whole 1” paster at a 100 yards. I had to let the gun sit for a few minutes and then went to 3 shot groups. Next time to the range I put my F class rifles mirage shield on the barrel so I didn’t have to deal with that.

That's GOOD to hear about the progress being made in getting the carbon fiber material to better wick the heat away. I guess there's still no available detail about how this improved conductivity technique compares to the conductivity of steel???

Given that the carbon itself is a much better conductor of heat than steel, it seems the main limitation for improving the "wicking" of the heat from the bore (from the steel core, if you will) is the resin/epoxy used. Having had a high interest in what can be done with carbon materials since the 1970's, I feel maybe over time this issue over the amount of epoxy used can be reduced as technology moves along with material like Graphene or Carbon Nano-Tubes??? Then maybe we'll be able to get CF barrels that can perform well in environments like we have in Arizona summers.

For those who might like to know what some material's conductivity are, here's a little chart (note that shown for Graphene. . . an amazing material ):

 

[Hohn]

That’s the problem. The part gets destroyed. How do you make a barrel and anywhere during the process test it with out destroying it?

Frank, our approach is that we validate our process with the destructive assessment. Then once we trust the process, it’s just spot checks from there.

Because you guys single point cut, you do not add any residual stress to them in your process. So any residual stress would have to be there before you guys got the blanks. And since I’m sure you get them normalized, you should essentially have a barrel as that’s nearly stress free.

Really, only a cryogenic treatment to the blank would likely show a measurable reduction in residual stress. And that’s under lab conditions. I doubt one could see it on target except under severe abuse.

 

[Franko]

I have been considering a carbon fiber barrel and am wondering if they will have reduced barrel whip compared to a similar weight steel contour (say a Bartlein #1 contour vs the carbon fiber barrel). I have read in a few places that carbon fiber barrels reduce barrel whip but it would be nice to hear it from the "horse's mouth" so to speak...

 

[rhovee]

I have been saying for years that Bartlien or someone else needs to offer a carbon barrel. Proof has dominated the scene and is a hit or miss with there barrels. I have some now. And when it comes to re-barreling, your kinda stuck. I do appreciate that Frank isn’t stating false advertisement. To me, they look cool and thats about it. I don’t see them being more accurate than a Bartlien #3 or 3B fluted that is the same weight as the M24 carbon.

 

[mauser284]

ON the contrary, carbon fiber actually resonates very well, which is why it is used to make cellos and violins and guitars. It has a very high Q value, but it varies with weave and fiber orientation and such.

Also used to make Bb Saprono trumpet bells.

 

[mauser284]

Anyone that offers these for sale is just in it to sell you a solution looking for a problem. There is absolutely ZERO research or science behind carbon fiber wrapped barrels. I hope at some point someone sues them for all that they are worth because it is criminal to make such claims with ZERO science or engineering to back up their claims. Given the premium they demand for such things it ought to be considered theft. If I machine my wrench or ratchet body down and replace that steel mass with carbon fiber my wrench or ratchet does not work better for it's job and it is not more rigid, stiff or stronger. Their is a reason they do not make automotive pistons, camshafts, connecting rods, crankshafts, heads or blocks from carbon fiber let alone carbon fiber wrapped....LOL Looks like I will never buy a Bartlin barrel I just hope Brux, Krieger, Shilen and Douglas do not go there so I can keep buying great barrels from people that are not going to insult my intelligence for marketing nonsense.

 

[FrankG]

The best non-destructive approach is process control of the material during manufacturing... which I suspect Bartlein already has in place!

Besides other things....I tell guys this.....

If there is stress in the blank it will show up during contouring of the barrel. It will get a bow in it (our terminology for being bent per say). If the barrel gets a bad bow in it it gets scrapped. The customer never sees it.