Carbon Barrel quality?

[Tycon]

I was thinking about buying/building a 7mm with a carbon barrel, but came across a post that said "carbon barrels are a technological flop".
There was no further questioning or explanation on that in the rest of the forum though! So.... What is everyones thoughts on a carbon barrel? I want to keep the gun light enough for hunting, so I'm not trying to compare to a big steel one.

 

[coyote]

Carbon fibre barrels still have a steel barrel inside I think the idea behind it was to make it stiffer by overlaying it with carbon fibre while keeping it light ,at least this is my take on it.
If you want a hunting barrels why not use a sporter profile between 2 1/2-3 lbs this way it will keep the weight down.
Btw lighter profiled barrels are still very accurate they just heat up faster and give more recoil , a hunting rifle only needs to shoot 1 or 2 shots in most circumstances.

I have also never seen a carbon fibre barrel in any of the matches I have attended.

 

[Gobc]

I did a bit of research on these out of curiosity. Mainly because Proof Research claims that the carbon "whisks away the heat". Before I get to that, I will say that carbon fiber can be very stiff and very strong if manufactured correctly. Like the above post, the barrel has a steel shank in the middle. So the overall barrel can be very light, and still very rigid. There is no real reason here why the barrel couldn't be very accurate.

Now we get to the heat thing. In my research, a lot of people were amazed on how the barrel isn't hot after being fired many times. And here is where Proof is saying how the carbon get's rid of heat. Heat transfer 101: Heat moves from hot to cold. If your barrel isn't hotter than the ambiant air, it's not heat isn't being dissapated to the environment. What people are describing is called an "insulator", and i'm sure you've heard the term many times before.


So in my opinion, I cannot see these things holding up after a large string of shots. I think they would make excellent hunting rifle barrels, as only 1 or 2 shots will be fired at the time, and there will be a great weight reduction to the rifle. But for serious target shooting, I can just see the heat building up inside the barrel, until the adhesive used in the carbon fiber wrap gives way.

Some people have said these things can go all day without any problems, and in some cases people reported failures. Not sure if these were "Proof Research" barrels. But I'm not a believer because everything I know about thermodynamics and heat transfer says that that carbon wrap is an insulator, not a conductor of heat. Again, in my research, a materials engineer who speacialized in carbon fiber said the same thing. The only carbon fiber barrel I would buy would be for a 22.

 

[owlowl]

Gobc is absolutely right.

Thermal conductivity (ability to transfer heat) in W/m•K:

• Steel is ~ 50 (carbon) to ~8 (high stainless)
• Carbon Fiber in Epoxy 5-7 in plane 0.5-0.8 transverse
• Air (not moving) 0.026

This is how "plane" looks like:

This is how transverse looks like:

Notice at direction of the fibers withed along the barrel or melted standing up.

Anyway, you see that steel, especially carbon steel is conducting heat way better than any fiber. But more importantly AIR is conducting heat WAY WAY less.

Regardless, the heat is created in the inner barrel and it is transferred in steel to outer barrel. You can't possibly "pull" more heat from the inner barrel "faster" then steel between inner and outer barrel can transfer. Think about regular cooler with food. No matter how your wrap it outside with foil, copper, put it in water or whatever - the inner temperature will be stable because it is locked by the amount of heat transferring thought the thick plastic sides of the cooler.

Your problem is also not the conductivity of outer layer barrel itself, but the heat conductivity of surrounding air and air thermal capacity (how much heat it can suck into itself without transferring it further).

The only way to significantly increase heat transfer from a barrel is either add a significant heat absorption - think water jacket for instance like maxim mg. This is because water has excellent thermal capacity and can "suck" heat into itself and you can put move water from and our of the jacket. Or, second option, significantly increase square of the outer surface contacting with air, adding fins or increasing barrel diameter.

Anyway long story short, carbon fiber wrapped barrel like this:

is in fact more insulated from the outside and will heat up INTERNALLY faster and cooldown internally slower then simple steel. If the whole idea of cooling down or transferring heat from a barrel by applying any material outside of a barrel could possibly work, we would see copper (401 W/m•K) or aluminum (205 W/m•K) sleeves or barrel jackets long time ago. There was plenty of copper and aluminum in the last 150 years to work with, but no one put it outside machine gun barrels so they would heat up less cool down faster.

It is pure marketing BS. For extra money I'd rather have my barrels gold plated (310 W/m•K by the way)

 

[hend238]

It is pure marketing BS. For extra money I'd rather have my barrels gold plated (310 W/m•K by the way)

I love it! So much of what we are sold these days is exactly that - marketing BS. I understand that manufacturers need to continually find inventive ways to sell and resell their products. We are all guilty of falling for it. I look forward to reading the counter arguments. I think I will start another thread stating that fluting a barrel doesn't make the same barrel stiffer. Thanks for the great post.

 

[owlowl]

I think I will start another thread stating that fluting a barrel doesn't make the same barrel stiffer.

There is no need for a thread at all, it is kinda obvious. A round barrel is stiffer than a fluted barrel of the same outer diameter just purely due to the fact there is more steel in the round barrel. A fluted barrel of the same diameter however has greater outer surface such that there is more air contact and cooling is slightly better than of a round barrel of the same diameter.

Spiral fluting also has zero magical properties. A plain round barrel will always be better for the same diameter in everything but weight. So in fact only deep flutes present real sizable advantage in both air contact surface (cooling) and weight savings. However one should note that cutting flutes happens on the last stage of barrel process and are cold cut. During that cutting, especially for the deep flutes, you will create a stress in the steel which you won't be able to fix unless you heat the steel up to lower critical temp and cooling it down uniformally - perform stress relieving. It can not be done really because your will have to redo the rifling after that. So, if you cut flutes very deep or very aggressively you are weakening and stressing the barrel.

But flutes require quite a bit of a metal work and they are visible to potential customer, unlike internal steel grain and whatnot, so for the purpose of selling more expensive rifles they'd better be fluted for sure. Wait until they found a way to cover flutes in carbon fiber, that would beat sliced bread for sure )

 

[coyote]

Owlowl you are right about flutes not making a barrel stiffer imo you cant make something stiffer by removing material.

 

[Gobc]

What you guys suggest about fluting is true, when comparing the original round barrel to the fluted barrel. But if you consider a round barrel vs a fluted barrel with a larger diameter, but same weight per inch, the fluted barrel will be stiffer because more of the material is distributed farther from the barrels center. However, both barrels will be equal weight instead of a lighter/less stiff fluted barrel. One would obviously have to work out the dimensions before making the final cut however. I wonder how many people or gunsmiths consider this when profiling their barrels.

 

[hend238]

There is no need for a thread at all, it is kinda obvious.

I was being a smart ass.

 

[owlowl]

Well I can put that into perspective a bit if you like.

For a barrel with diameter of 17mm:

• Increasing length from 23 inches to 25.5 inches will add around 100 grams
• Cutting flutes on 25.5 inches will save 88 grams, still will be more than 23 inches.
• Cutting flutes on 23 inches will shave around 73 grams.

Taking a 19mm diameter instead of 17mm:

• This will increase weight of a 23 inch barrel by 332 grams
• Fluting 19mm by 23 inch, will reduce weight by 130 gramms
• If you increase the length to 25.5 inches, this 19mm will be 130 grams more.
• If you flute 19mm by 25.5 inches, it will drop around 190 grams in weight

Take 22mm diameter barrel 24 inch long:

• Adds up 180 grams compared to 23 inch 19mm.
• Cutting flutes on that takes off 270 grams.

Now lets look at these numbers. They show that no fluting can compensate weight of thicker contours. On a 17mm barrel fluting is saving less than 100 grams on a 25.5 inch barrel. As we know round 17mm will be stiffer than 17 fluted. But 17mm diameter does not have any extra real stiffness to trade for I think. Heat dissipation on 17mm barrel fluted or not is negligible, because you wont shoot a lot from a pencil barrel like that, so heat is not really a problem I would say.

Cutting flutes on thick barrels do present weight savings, but they are heavier nevertheless. If they are heavy you are probably want to shoot a lot and from static position, in this case why flute it at all if round contour is still better for that than fluted.

I'm not saying you should not flute, I'm just trying to point out that it seems to me that any advantages of that are imaginary considering, while cost is not.

On the other hand. for aesthetics I like straight fluted, and don't like spirals by the look of it. And to be honest, in my world aesthetics plays bigger part than functionality. But I would not mix the two, real functional advantages have very little to do with it.

 

[Trevor60]

The dispute seems to stem from peoples belief that a fluted barrel of the same dia is stiffer as a straight barrel. This is simply not correct.

I fluted barrel of the same weight is stiffer then a comparable non fluted barrel.

A stiffer barrel produces less vertical
A fluted barrel of the same weight is stiffer and will produce less vertical then a comparable non fluted barrel.
A fluted barrel has more surface area then a comparable non fluted barrel of the same weight resulting a better cooling

Fluting can be used to make weight if you shoot competitions

My example as comparing to a heavy palma barrel at the crown whose dia is .90 to .93 to a fluted barrel of the same weight when the dia is 1.01

is it worth the cost. that is up to you to decide

if you don't want to go with fluting you can look into barrel tuners.

this thread got really side tracked.

carbon wrapped barrel yea or nay.. you are shooting a open class caliber in a pencil thin barrel with carbon wrapping. irrespective of the carbon wrapping if you shoot anything more then a nominal amount of rounds each year. a 7mm barrel in a rem mag or something similar will burn out your throat in the same number of rounds as a straight 1.25" barrel but carbon wrapping cost almost twice as much per barrel.

Thank you
Trevor

 

[owlowl]

Sidetracked, yes.

Point of the thread was that carbon fiber barrels are snake oil and can possibly do what manufacturers claim they do.

 

[alberta tactical rifle]

Sidetracked, yes.

Point of the thread was that carbon fiber barrels are snake oil and can possibly do what manufacturers claim they do.

Well for what our experience is worth. The manufacturers claim their CFW barrels are much lighter than the same contour conventional barrels, and that is 100% true.
They also claim that CFW barrels are equally accurate to conventional barrels, and owning several rifles with CFW barrels I would agree. A rifle that shoots .2s is certainly an accurate rifle.
They claim they dissipate heat better, well my experience is that they get REAL hot REAL quick and cool down REAL quick. Much faster than the same contour conventional barrels in the same caliber.
They claim a lesser degree of POI shift from heat, in the 3 years I have been running them on several of my rifles, this seems to be true.

Not all CFW barrels are equal, my experience with 1 maker was very poor, our experience with Proof barrels have been extremely positive given the feedback from several hundred clients to date who have elected to use them.

YMMV

 

[owlowl]

The manufacturers claim their CFW barrels are much lighter than the same contour conventional barrels, and that is 100% true.

If have same outer diameters and carbon fiber has any thickness (not just a film), it is obviously that the barrel with carbon fiber has less steel underneath. But you cannot imply that you replace a millimeter or two of steel with carbon fiber without affecting the rigidity of the barrel. Carbon fiber barrel in this case will be less rigid wont you agree? 1mm of fiber flexes much more than 1mm of steel.

They also claim that CFW barrels are equally accurate to conventional barrels, and owning several rifles with CFW barrels I would agree. A rifle that shoots .2s is certainly an accurate rifle.

"Equally accurate" means there is no reason to apply carbon fiber, does it not?

They claim they dissipate heat better, well my experience is that they get REAL hot REAL quick and cool down REAL quick. Much faster than the same contour conventional barrels in the same caliber.

Well, first of all, anecdotal evidence says that people also note the opposite - the barrel does not feel that hot to touch. So lets assume there are at least some manufactures which do it in a way that creates more insulation, and lets assume your had experience with another - "good" type. Fair enough. Have you seen any results on temperature measurements done with any instruments measured in better units than "looks like" and "pretty quick"?

I can give you a hint, might be valuable for your business actually.

1) Google "FLIR ONE" second gen thermal imager, for ios or andoroid - $250 USD, cheap as peanuts
2) Take 2 rifles of a same caliber side by side, one with carbon fiber on top and another with regular steel of the same outer diameter.
3) Take a shot from one, record the heat map and temperature reading, record how it changes in 5 minutes, fire another rifle do the same.

Compile that together in a video featuring your premier manufacturing facility and arrive to scientific conclusion. We all would love to see that, it would take you half a day, but would be a great ad for your company.

Don't get me wrong, but if you are in a business of making rifles and you judge something in terms of "really quick" it doesn't really sound substantial. You have all the tools and resources to verify claims based on pure evidence, don't you think?

 

[Tycon]

I'm with owlowl, I want to see it! I'm not interested in knocking the barrel's, I am interested IN them.
It seems like the argument is that carbon is an insulator, which I am somewhat forced to agree with after the science lesson owlowl gave us, and also that it's not as good at heat dissipation as a steel barrel of equal contour. But what about the difference between having a more rigid barrel than a small contour, but keep it as light as one? Coyote is right, you can get accuracy out of a sporter, but you get the recoil, and maybe more inconsistencies due to rigidity. For these purposes is it worth it? What is everyones thoughts on the comparison between the carbon and the sporter profile?

 

[owlowl]

To be fair, I'd like to note another possibility, that IF you consider the following:

A) plain steel barrel diameter N mm
B) carbon fiber barrel diameter M which is ON TOP of the contour N plain steel barrel (M = L thickness of carbon + N initial steel )

Then IF your carbon fiber layer is of a significant thickness AND is it formed with as little epoxy and plastic base AND fibers are directed in plane. In this case you might significantly increase the outer surface contacting air. This would be:

1) better than plain steel barrel of lesser overall diameter N
2) but weight still MORE than plain diameter N barrel (for the weight of carbon)
3) but yet again weight significantly LESS than plain steel barren of diameter M

Just saying, so we don't get fixated on one scenario. The only reason you can use non metal on top of a barrel is to use thick layer to create way bigger final outer diameter for fraction of a weight. For the same diameter thick steel is superior in everything but total weight.

PS
By the way want an idea to patent? Make copper foam sleeves on top of the barrel. Fraction of the solid copper weight, outstanding thermal conductivity, amazing metal to air contact surface, still very light to affect solid steel barrel vibration.

The only thing you need to figure out is the foam to barrel contact. But i solve you this issue to - make regular barrel, make deep flutes in it, put copper foam into the flutes, such that steel will hold it from 3 sides. If only copper was so hi-tech as carbon fiber.

 

[Shawn_338]

I don't really care about what ppl read on the Internet, at the end of the day the only way to know for sure for yourself is to try it. So I did a carbon wrapped barrel is lighter than the same contour barrel in steal, does it dissipate heat faster? Maybe. Would I run a carbon barrel in a br match? No. But I do hunt with one and it shoots as straight as any of my comp guns. And it looks really good doing it!

 

[Gobc]

I would love to see some internal temperatures of a carbon fiber barrel vs a steel one. Until then I'll stick to my original opinion. But thanks to ATRS & Shawn for weighing in, and i'm glad the products are working for you guys.

 

[alberta tactical rifle]

If have same outer diameters and carbon fiber has any thickness (not just a film), it is obviously that the barrel with carbon fiber has less steel underneath. But you cannot imply that you replace a millimeter or two of steel with carbon fiber without affecting the rigidity of the barrel. Carbon fiber barrel in this case will be less rigid wont you agree? 1mm of fiber flexes much more than 1mm of steel.


"Equally accurate" means there is no reason to apply carbon fiber, does it not?


Well, first of all, anecdotal evidence says that people also note the opposite - the barrel does not feel that hot to touch. So lets assume there are at least some manufactures which do it in a way that creates more insulation, and lets assume your had experience with another - "good" type. Fair enough. Have you seen any results on temperature measurements done with any instruments measured in better units than "looks like" and "pretty quick"?

I can give you a hint, might be valuable for your business actually.

1) Google "FLIR ONE" second gen thermal imager, for ios or andoroid - $250 USD, cheap as peanuts
2) Take 2 rifles of a same caliber side by side, one with carbon fiber on top and another with regular steel of the same outer diameter.
3) Take a shot from one, record the heat map and temperature reading, record how it changes in 5 minutes, fire another rifle do the same.

Compile that together in a video featuring your premier manufacturing facility and arrive to scientific conclusion. We all would love to see that, it would take you half a day, but would be a great ad for your company.

Don't get me wrong, but if you are in a business of making rifles and you judge something in terms of "really quick" it doesn't really sound substantial. You have all the tools and resources to verify claims based on pure evidence, don't you think?

I was going to reply with a long explanation, but decided I was only wasting my time. Apparently you know everything already and do not possess an open mind.

 

[owlowl]

I was going to reply with a long explanation, but decided I was only wasting my time. Apparently you know everything already and do not possess an open mind.

I'm sorry if you took that as an offense or a joke. I didn't mean to insult you in any way.