VLD Pilot
Well-Known Member
Gotta admit, they look pretty sharp as well. I did mine for weight savings carrying on long haul hunts. Probably will save a pound or two over all but as much as the weight savings, it's a good looking barrel.
Why use a carbon wrapped barel?
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I've never owned one so someone is going to have to help me out on this. Carbon has incredible natural vibration dampening properties. Has anyone noticed wider accuracy nodes vs comparable weight steel barrels? No doubt a bit hard to quantify, but i can't help but wonder if it would reduce the amplitude of the vibrations and make nodes bigger or easier to find.
djm670
Well-Known Member
In your previous statement you stated: "WE do cool the chamber and barrel by both a huge surface area (>300%) and active air flow thru the barrel."
Can you help me understand how much of the cooling is due to the surface area vs the airflow through the barrel? And how much ambient air flows through the barrel between rounds? I am assuming it (the airflow) is high velocity? Since you are talking rapid fire of many rounds.
I am not trying to be combative, I am trying to understand and learn what and how this is being done. I have worked in the thermal industry most of my life, albeit the automotive end of it, and not the manufacture of rifle barrels.
Thanks
I have a 26" proof cf barrel. I have been thinking about this a while myself. I can't complain about mine but I won't do another one. In hindsight, Instead of spending more money for a lighter cf barrel, I would put that money towards a very light action, a very light stock and go with a traditional stainless steel barrel. My opinion is that if extra money is going to be spent to lighten a rifle, the barrel should be the last part on the list to spend more to go lighter.I pulled my 22" #5 fluted Benchmark barrel tonight, and out of curiosity I put it on the scale.
Its .720 at the muzzle and shoots .2s with a suppressor. I paid $450 for the blank
So why is carbon fiber all the rage right now
View attachment 238760
This is an interesting and relevant debate! Some science/fact sprinkled in with a lot of opinion and heresy. I have been weighing the pros and cons of fluted stainless and carbon fiber wrapped for my next mountain rifle.
As an aerospace mechanical engineer and metallic and composite part manufacturer for 30+ years I have seen the transition of many aircraft parts from aluminum to carbon fiber. I have made many of these trade studies myself. Sometimes CF parts are better suited sometimes they are not. Rather than throw out a carte blanche recommendation I will offer a few of my primary concerns with CF.
Coefficient of Thermal Expansion (CTE) mismatch:. Different materials exhibit different CTEs. When you bond carbon fiber composite to steel the two materials expand and contract at different rates. This creates a lot of stress at the bond joint and can lead to adhesive failure (delamination). This would be most likely to occur where the temperature difference is highest (chamber end).
Contamination:. Composite manufacturing is very subject to contamination. Modern composite processing is labor intensive and usually involves extended cures at elevated temperature and often pressure or vacuum. Foreign material, including moisture, is difficult to control and can disturb the carbon fiber - epoxy bond. These internal defects can propagate over time. My concern is that a lot can go wrong and it's easy to cheat to save manufacturing cost.
Environmental Susceptibility: it is well established that many epoxy resins are susceptible to moisture, UV light and various chemicals. Most aerospace parts receive advanced primers and coatings to protect against these.
These are some of my primary concerns and things I will want to discuss with barrel manufacturer's.
As far as weight my calculations show that a straight fluted light contour stainless barrel can be made as light as the common profile carbon wrapped barrels.
As far as heat transfer, there's no magic. If the thermal conductivity of steel is higher than that of the net, in axis thermal conductivity of the steel-carbon-epoxy assembly, then the steel barrel will transfer heat better. Comparing the perceived touch temperature of two surfaces is not a valid measure of thermal conductivity.
As far as harmonics, the natural frequency of part/system increases with stiffness and decreases with mass/weight. So for steel and CF wrapped barrels of equal weight, the stiffer barrel will have a higher natural frequency.
Hope this helps you make an informed decision! I still haven't decided which way I am going. I have some concerns with steel too.
As an aerospace mechanical engineer and metallic and composite part manufacturer for 30+ years I have seen the transition of many aircraft parts from aluminum to carbon fiber. I have made many of these trade studies myself. Sometimes CF parts are better suited sometimes they are not. Rather than throw out a carte blanche recommendation I will offer a few of my primary concerns with CF.
Coefficient of Thermal Expansion (CTE) mismatch:. Different materials exhibit different CTEs. When you bond carbon fiber composite to steel the two materials expand and contract at different rates. This creates a lot of stress at the bond joint and can lead to adhesive failure (delamination). This would be most likely to occur where the temperature difference is highest (chamber end).
Contamination:. Composite manufacturing is very subject to contamination. Modern composite processing is labor intensive and usually involves extended cures at elevated temperature and often pressure or vacuum. Foreign material, including moisture, is difficult to control and can disturb the carbon fiber - epoxy bond. These internal defects can propagate over time. My concern is that a lot can go wrong and it's easy to cheat to save manufacturing cost.
Environmental Susceptibility: it is well established that many epoxy resins are susceptible to moisture, UV light and various chemicals. Most aerospace parts receive advanced primers and coatings to protect against these.
These are some of my primary concerns and things I will want to discuss with barrel manufacturer's.
As far as weight my calculations show that a straight fluted light contour stainless barrel can be made as light as the common profile carbon wrapped barrels.
As far as heat transfer, there's no magic. If the thermal conductivity of steel is higher than that of the net, in axis thermal conductivity of the steel-carbon-epoxy assembly, then the steel barrel will transfer heat better. Comparing the perceived touch temperature of two surfaces is not a valid measure of thermal conductivity.
As far as harmonics, the natural frequency of part/system increases with stiffness and decreases with mass/weight. So for steel and CF wrapped barrels of equal weight, the stiffer barrel will have a higher natural frequency.
Hope this helps you make an informed decision! I still haven't decided which way I am going. I have some concerns with steel too.
Frank Green with Bartlein answers some questions here:
www.snipershide.com
Bartlein Carbon Wrapped Barrels
I just saw a facebook post by GA Precision about Bartlein offering carbon wrapped barrels. This should be very interesting....... Anyone else see this?
www.snipershide.com
Idaho Hunter1
Well-Known Member
Thanks Len!
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I'm not proud.
I would disagree that you can make a fluted barrel the same weight as a cf barrel. The minimum wall thickness is generally .150 per side across the barrel industry. That means the flutes can only go that deep. That is extra steel that is not there when turned down for CF.
The CTE is still interesting to me. It shows CF is lower on the scale, however, the Specific Heat has to come into this too, doesn't it? No expert, but I know the amount of energy needed to heat a pencil barrel v heavy barrel is much less. The CF (with associated resin) have much different Specific Heat than the steel.
Here are some numbers to play with.
CF barrel steel volume = ~10in^3
Steel barrel (Remington Varmint contour) volume= ~20in^3
Obviously, twice the volume of steel to heat and cool without taking into account the CF CTE. Curious what the numbers show for time of heat dissipation....
edit- numbers were off
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The rifle balance is gonna be awfully front-end weighted. Miserable for a carry rifle.
Lighter CFW barrels that are stiffer than steel barrels sounds darn good to me, for my backpack hunting.
I own one Proof CFW barrel in 30 SM and have hunted with it for two years now. It's acceptably accurate and a pleasure to carry. Very nicely balanced. I also reduced weight with the McMillan Edge stock, a 16oz scope, and 7075 aluminum scope rings, and a titanium muzzle brake.
I now own two more CFW barrels, both Bartleins.
One in 30 SM, and one in 338 Lapua Rogue. Haven't fired either of them yet, so I can only comment that the exterior finish on the Proof carbon is nicer than the exterior finish on the Bartlein carbon, but that the bore finish on the Bartleins looks nicer than the Proof. Also, the Bartlein CFW barrels are a bit heavier than the Proof, but I knew that prior to purchase.
I'm an engineer with a good background in, and understanding of, heat transfer. I would never purchase a CFW barrel for the purpose of improved cooling. Some members trained and practicing in the field of heat transfer have posted competently and credibly on this subject, as have I in the past. I both understand, and agree, with their assessment and the science supporting their assessment. If you want to believe otherwise, it's your God given right to be wrong. Having stated that, I don't rapid fire any of my LR hunting rifles, whether they have SS, CM, or CFW barrels, so it's not a big concern for me. If you've got the need to shoot prolonged rapid fire mode, I'd advIse against a CFW barrel, unless you believe higher bore temps are a good thing. I'll never put a CFW barrel on my AR15, a rifle that I do sometimes shoot in rapid fire mode for fun and games.
CFW barrels will not provide cooler bore temps, as some manufacturers claim. I believe this promotional tactic gained credibility because CFW barrel shooters commonly state the exterior of their carbon barrels feel cooler to their touch. They feel cooler because the CFW is an insulator compared to steel, and the CFW reduces the rate of heat transfer from the bore to the surface. Which is to say, the heat remains in the steel liner core for a longer period of time.
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Can one of you engineers throw some numbers together for the time required to cool back down? I posted the volume of steel for each but don't have the experience in running the other equations. We've had enough back and forth in this thread. We need numbers to put it to rest.
edit: ran the numbers for a cf 308 i built v a rem varmint i have
cf barrel 10.03in^3
steel rem varmint 20.58in^3
edit: ran the numbers for a cf 308 i built v a rem varmint i have
cf barrel 10.03in^3
steel rem varmint 20.58in^3
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It will never be put to rest by any attempted efforts to answer your question.
All you need to know to determine which material transfers heat faster, is the thermal conductivity of the steel in a barrel, versus the thermal conductivity of the CFW media.
The higher the thermal conductivity coefficient, the faster heat is transfered thru the media by conduction.
When a Christensen Arms' engineer provided the thermal conductivity for their CFW to one of our Forum members, it was about 1/4 that of gun barrel steel. Good luck trying to get a thermal conductivity value from the barrel manufacturers... I suspect that Christensen Arms engineer is no longer employed.
The brighter side of the issue is, the lower heat transfer rate thru the CFW isn't a non-starter or deal breaker, given reasonable rates of fire used by most knowledgeable LRHs. Guys that understand rapid rates of fire from fire-breathing dragons shorten throat and barrel life. I'm well schooled in heat transfer. I understand CFW barrels transfer heat less efficiently than steel barrels. I now own 3 CFW barrels. I don't worry about it for my application and use.
All you need to know to determine which material transfers heat faster, is the thermal conductivity of the steel in a barrel, versus the thermal conductivity of the CFW media.
The higher the thermal conductivity coefficient, the faster heat is transfered thru the media by conduction.
When a Christensen Arms' engineer provided the thermal conductivity for their CFW to one of our Forum members, it was about 1/4 that of gun barrel steel. Good luck trying to get a thermal conductivity value from the barrel manufacturers... I suspect that Christensen Arms engineer is no longer employed.
The brighter side of the issue is, the lower heat transfer rate thru the CFW isn't a non-starter or deal breaker, given reasonable rates of fire used by most knowledgeable LRHs. Guys that understand rapid rates of fire from fire-breathing dragons shorten throat and barrel life. I'm well schooled in heat transfer. I understand CFW barrels transfer heat less efficiently than steel barrels. I now own 3 CFW barrels. I don't worry about it for my application and use.
I disagree that it wont be put to rest. Someone with good knowledge of these formulas could post numbers and clear this all up. If no one else does, I'll figure it out and post.
