Fluted Bartlein vs Proof Research sendero contours

[5RWill]

Lancet what are the weights on those rifles?

Seems also that either proof retail dropped or everyone is having a sale? Redhawk and CORE off them at 730$

Our 3B was 350$ + 175$ to flute. Though 150$ if i had sent it directly to Kampfield, i let SAC outsource it.

 

[Pdvdh]

Here are some facts for those seriously interested instead of the wild speculation being spouted in this thread. The thermal conductivity and specific heat capacity of the two barrel materials CAN NOT be compared like some individuals in this thread are trying to do because one of the materials is homogenous and the other is not. This is from the Christensen Arms engineer. If you are really interested you can find this information repeated from the aerospace engineers.

Hello Ryan,

The thermal conductivity of carbon fiber material, generally is not rated as it varies between many factors. Several key factors that play into the thermal conductivity, or diffusivity, are: mass, volume, ply orientation, resin saturation, and the primary material components as well. There were test performed years ago, before my time; however, they have been archived and it would take some digging to get them out. I can easily supply you the engineering behind the claims, especially at a face value, when considering only the thermal conductivity, density, and specific heat, see below:

Thermal Diffusivity (α): The ability of a material to conduct thermal energy relative to its ability to store thermal energy. Materials with a large thermal diffusivity will respond quickly to changes in their thermal environment, while materials of a small thermal diffusivity will respond more sluggishly, taking longer to reach a new equilibrium condition.




Example: Carbon Vs. Steel

Carbon Steel: k = 60.5 w/m*k, ρ = 7854 kg/m3, cp = 434 J/kg*k

α = (60.5 w/m*k)/ ((7854 kg/m3)*( 434 J/kg*k)

α = 1.80 E-5 m2/s

Carbon Fiber (25% epoxy):

Parallel to fibers: k = 11.1 w/m*k, ρ = 1400 kg/m3, cp = 0.982 J/kg*k

α = (11.1 w/m*k)/ ((1400 kg/m3)*(0.982 J/kg*k)

α = 8.07 E-3 m2/s

Perpendicular to fibers: k = 0.87 w/m*k, ρ = 1400 kg/m3, cp = 0.942 J/kg*k

α = (0.87 w/m*k)/ ((1400 kg/m3)*(0.942 J/kg*k)

α = 6.60 E-4 m2/s

This means that carbon fiber epoxy parallel to fibers has an approximate thermal diffusivity of 450 times greater than carbon steel and perpendicular is approximately 37 times greater.

The fact that the user does not feel the barrel getting hot is due to the volume of the barrel and rapid heat dissipation through the length of the barrel, not just the chamber or muzzle end. We run a larger contour than that of standard barrel contours, unless ordered as a heavy barrel contour. A proper test would be to use the same contour steel barrel and compare against a carbon wrapped barrel of the same finished contour. This test can be accelerated when using a semi-auto rifle platform.

I know this isn't the graphs and charts that you were looking for, but this is the science behind the claim. I hope this helps. If we conduct another test in the future I will be sure to get with Eric and help with information/education.

Thanks,

Casey Hill
Design Engineer
Christensen Arms
[email protected]
(435)528-7999 ext. 427

Thank you for seeking out and producing the Christensen Arms values for the thermal conductivity of their carbon fiber material. I wanted to give you 24 hours to bath in the false-belief that the carbon fiber wrap on your barrel will conduct heat from the bore to the surrounding atmosphere better than an all steel barrel.

Now that the thermal conductivity of the carbon wrap material has been provided, both parallel and perpendicular, to the carbon fibers, I can tell you how much better the carbon fiber wrap insulates the steel liner, compared to steel.

In the direction most pertinent to heat transfer (because the heat must only transfer across the short cross-section thickness of the carbon fiber wrap) perpendicular to the bore, the carbon fiber wrap insulates the bore temperature 60.5 / 0.87 = 69.5 times more effectively.

In the direction least pertinent to heat transfer (because the heat must transfer through the length of the carbon fiber), the carbon fiber wrap insulates the bore 60.5 / 11.1 = 5.4 times more effectively.


What is thermal conductivity?
When a system gains heat, it stores some of its heat energy and transports the remaining heat energy to some other system. The ability of a system to transport heat energy is referred to as Thermal conductivity of the system. Basically, it is a Transport property of a system.

Thermal conductivity is represented by k. The unit of thermal conductivity as we have seen earlier is W/m*K.

What is thermal diffusivity?
When a system gains heat, it stores some of the heat energy and transports the remaining heat energy to some other system. As we have seen, the ability of a material to transport heat energy is referred to as thermal conductivity. The heat storage capability of a material is referred to as heat capacity of the material. The heat capacity of a material is represented by Cp.

Thermal diffusivity represents how fast heat diffuses through a material. It is defined as

Note that, the thermal conductivity represents how well a material conducts heat and heat capacity Cp represents how much energy the material stores per unit volume. Therefore, the thermal diffusivity of a material can be viewed as the ratio of the heat conducted through the material to the heat stored per unit volume.

How is thermal diffusivity related with thermal conductivity?
A material with a higher thermal conductivity or lower heat capacity will have a large thermal diffusivity. The larger the thermal diffusivity, the faster the propagation of heat into the medium. A small value of thermal diffusivity means that heat is mostly absorbed by the material and a small amount of heat is conducted further.

If you want to consider the property of heat storage, in addition to heat transfer efficiency, then confuse the matter by discussing and comparing thermal diffusivity. If you're solely interested in which material transfers heat most efficiently, then discuss and compare thermal conductivity of the two different materials.

For the curious, place your carbon wrapped barrels in your chest freezer, or outside if you live in an area with frigid outdoor temperatures. Then pick the barrel up by the carbon wrap, versus the steel chamber. Which feels colder to the touch? The material that insulates the best (reduced heat transfer) will feel warmer. The material that conducts/transfers heat energy best will feel cooler. Would you rather sit on a steel toilet seat in your outhouse in frigid winter temps, or a toilet seat constructed of rigid foam insulation or carbon fiber? If you want to do the business in reasonable comfort, you'll select the carbon fiber with the lower thermal conductivity coefficient.

You've referenced Bryan Litz comment from his book twice now, to support your preference to believe against all odds. If Bryan Litz states that the carbon fiber material with the lower thermal conductivity coefficient will transfer heat via conductive heat transfer from the bore to the surrounding atmosphere at a higher rate than steel with the higher thermal conductivity coefficient, just say that. Or request Mr. Litz post that position in this Thread. I'll be waiting...

phorwath,
Independent Engineer

 

[FURMAN]

You have been presented with the facts and you are wrong yet you continue to run your fingers over the keyboard. I will not argue with you. Think what you want it makes no difference to me as I have already stated. You seem to think, for some unknown reason, that I care for a split second about how fast my barrel cools. I own carbon barrels because they shoot just as accurately as any barrel I have owned at a fraction of the weight. I hunt the backcountry I will not carry extra weight for no reason. I do not think, after reading your last post, you even have a clue about heat transfer. Thermal conductivity is used in a heat transfer calculation with a constant heat source. Thermal diffusivity the only number that really matters outside of a system with a constant heat source. I am confident that the individuals reading this thread who care to know the facts will see through the speculation.

 

[lancetkenyon]

.280AI R700, Manners EH-1, 26" Proof w. Premier Light Tactical 3-15=8lbs 15oz
7RM R700, Manners EH-2, 26" Bartlein #3B fluted w. S&B 3-20=10lbs 9oz
6.5 SS R700, McMillan Game Scout w. Edge, 26" Bartlein #3B spiral fluted w. S&B 5-25=10lbs 10oz
.25-06AI R700, B&C Medalist, 28" Shilen #4 w. Vortex Razor Gen I 5-20=11lbs 6oz
.300RUM R700, McMillan Adjustable Game Warden, 28" Rock Creek Rem Varmint spiral fluted w. Premier 5-25=14lbs
6.5SS R700, Manners T2A, 28" Bartlein Rem Sendero w. Kahles K624i 6-24=15lbs 10oz

I am collecting parts for a new build. Not sure which exact route I am going to go quite yet.
Lone Peak TI SA .473" bolt face
Manners EH-4

Going to go with:

Proof Sendero Lite or Bartlein #2B or 3, probably either fast twist .224" for a .22-250AI or .22-243AI, or 6mm/.243 for a 6XC, 6x47L, etc. Thinking short, maneuverable, and light, like a 20-22".
Either Tangent Theta TT315M 3-15x50 or March F1 3-24x52

Should be a good long range varmint, long range steel, medium range antelope/deer rifle. A dream to carry, and fun to shoot!

 

[Pdvdh]

You have been presented with the facts and you are wrong yet you continue to run your fingers over the keyboard. I will not argue with you. Think what you want it makes no difference to me as I have already stated. You seem to think, for some unknown reason, that I care for a split second about how fast my barrel cools. I own carbon barrels because they shoot just as accurately as any barrel I have owned at a fraction of the weight. I hunt the backcountry I will not carry extra weight for no reason. I do not think, after reading your last post, you even have a clue about heat transfer. Thermal conductivity is used in a heat transfer calculation with a constant heat source. Thermal diffusivity the only number that really matters outside of a system with a constant heat source. I am confident that the individuals reading this thread who care to know the facts will see through the speculation.

You will not argue with me? Isn't that what you've been doing, with significant effort and time?
You don't care a split second about how fast your barrels cool? Then why engage in the effort to mislead others into thinking their carbon wrapped barrels cool faster than comparable sized steel barrels.
You understand the conundrum? Your Posts don't support your declaratory post/speech from the mountaintop.

"You seem to think, for some unknown reason, that I care for a split second about how fast my barrel cools." Never said that. Never thought that. I care to an extent when CF barrel manufacturers attempt to increase sales with false advertising. Thought I was clear about that.

There is no "the only number". You do understand that the equation for thermal diffusivity includes that other pesky number - the thermal conductivity coefficient? Maybe you missed that... failed to understand it... or prefer to ignore it...

Nobody I've ever talked with expresses notable concern over the momentary heat of firing one single cartridge - and bore overheating. The overriding concern is repetitive fire. You think repetitive fire doesn't approach the conditions of your hypothetical constant heat source? Close enough for me and others that would calculate heat transfer. Very aptly suited for conductive heat transfer analysis using the thermal conductivity coefficient.

Your confidence must be grounded in the need to feel good about your carbon barrel cooling rates (those cooling rates that you care less than a split second about), because you haven't the background to differentiate between supportive facts and misleading facts. The consequence being you'll settle for whatever feels good, no matter how flawed.

Maybe you'd have handled yourself better here if it weren't for that room full of carbon fiber wrapped barrels.

 

[AKdan]

Hey guys I figure I would throw out a few things as this is a place to learn a little bit more. I do not intend to argue, so I apologize if anything offends anyone. I really had a fun time "nerding out" doing a little research and this is what I found. I appreciate when I am given facts a figures, maybe sometimes known as "WAG's", for various things, but with the tidbit of sodium chloride, I prefer to verify the information provided is accurate. After reading the "definitions" , "facts , and "whatchamawhosits" I did a little google searching. I stumbled across a few sites that provide a little more information on the subject.

For reference this appears to be the website that information in Phorworth's post comes from. hhttps://medium.com/@lucidlearning314/thermal-conductivity-and-diffusivity-e6d3b5ee7ce5 I encourage a thorough read of the entire article.

I enjoyed reading the article found at: https://www.christinedemerchant.com/carbon_characteristics_heat_conductivity.html
There are several scholarly reads associated with this article with several studies base on carbon thermal properties. I Find this article discusses additional properties a little closer to the properties of carbon barrels that the OP was hoping to discuss.

I encourage researching more articles so that we all are a little more informed and not acquiring all of our information from a regurgitation of speculative information.

Barrels are judged almost purely by their performance. A good barrel is one that shoot very well. We all want to buy barrels that shoot better than we can. (or buy with the hope it make us shoot better). To say that a Carbon Barrel is an "insulator" and incinerating the metal liner is only true if the manufacturer uses an epoxy that inhibits the thermal transfer in the carbon. To say that a Carbon barrel reduces in heat caused by XX grains of powder is also not true. The heat introduced to the wear surface of the bore is independent of the outer construction of the barrel. Several people have tested round counts on both types of barrels and found similar wear on both resulting in a similar barrel life with similar use. Accuracy has been an issue for some steel and carbon barrel makers.....they usually struggle until the figure it out. There are both carbon barrels and steel barrels that shoot marvelously. make your own conclusion.

The OP was seeking information about accuracy and weight. As has been discussed many times over the mechanics of fluting a barrel (very minor effect on thermal transfer......and yes it is ALL steel...weird). The stiffness of a barrel has great effects on the harmonics of the barrel. The inherent stiffness compared to weight is highly favoring carbon barrels, though not saying it is necessarily stiffer than an all steel barrel as I have not actually measured it with two comparable barrels. HOWEVER, My 28" 338 proof barrel is significantly more stiff than my 28" 338 fluted medium palma barrel. Even more interesting is they both weigh the same. I am hanging a "noise snuffer" on the end of the tube so I wanted to add a little stiffness without the extra baggage. The gain almost lies in the ability to have a silly thick barrel that is extremely stiff (thick steel barrels are still to) but it is light weight like my thin fluted mountain whistly groovy barrel (anyone else notice their fluted barrel whistles a lot in the wind?). This gain comes at a significant cost $$$$, but to some it is worth it. The "dimensional stability" and "Stiffness" is what i paid an extra $300 over my "not so rapid cooling" fluted barrel. Accuracy for both barrels is exactly what I want so I love them both.

This has been quite fun to jump in on. I encourage more learning and studying the properties and mechanics of materials. Manufacturers spend a tremendous amount of money engineering tools and materials to provide a result that will support their passion to provide manufacturing in the firearms industry(yes this means sales). Figure out what your priorities for a rifle build are and base your decision on that. If you base your decision based on cooling rates I would suggest selling your Hawkeye and buying a Texas Instrument a torch and spend way less on precision machining.

Thanks,

Dan

 

[Pdvdh]

I expect the bore life of a CF barrel and a steel barrel will be identical at slow rates of fire. The bores in both barrels are made with the exact same steel. The steel is what's exposed to the flame thrower in both barrels.

The CF barrel will cool a tad bit slower but that difference is inconsequential for slow rates of fire.

So if there's going to be any benefit from a better cooling rate, that benefit will only begin to be realized at higher rates of fire sustained long enough for one barrel bore to elevate in temperature notably over the other.

So this is the focus of my criticism. The CF barrel manufacturers claim superior cooling. That their barrels cool more efficiently than steel barrels, which implies cooler temps and less overheating of the bore. Sustained higher rates of fire is what notably shortens accurate bore life.

The only scenario in which one barrel will benefit from shedding heat at higher rates is sustained fire. Sustained fire elevates steel temperatures in both barrels. Steel is an effective heat sink. It soaks up and stores a fair quantity of heat energy. Sustained high steel temperature is a close approximation to steady state heat transfer. In steady state heat transfer analysis, the thermal conductivity coefficient is the standard method of analytical solution. The Christensen Arms engineer has provided the thermal conductivity coefficients for their CF wrap and it's 69.5 times worse than steel in the shortest direction of flow, radially outward. A 69.5 times lesser rate of heat transfer thru the CF wrap than steel, by Christensen Arms own thermal conductivity coefficients. That's all there is. End of story.

However the Christensen Arms engineer disregarded the inferior thermal conductivity of their CF wrap, and diverted attention to thermal diffusivity, as if it more properly represents the rate of heat transfer thru their CF barrel wrap. Thermal diffusivity is useful in heat transfer analysis under transient, temporary, quickly changing temperature boundaries, like firing one single cartridge in a barrel. But I think we all recognize that the single shot fired isn't a temperature generating concern, and that neither barrel will offer a measurable advantage under single shot use. Also, IF the CF barrels were 100% CF, even the bore, the thermal diffusivity could be a little more pertinent. But their barrels have steel liners. Presenting the thermal diffusivity of the CF wrap as evidence of the superior cooling property of CF barrels is misleading, and flawed science.
The Christensen Arms engineer may not understand the flaw in his contentions. Perhaps that's the company line used to support the claim of better heat shedding, cooler running barrels. Or he may understand and gambled on smart AND clever, to spin a tale which supports their advertising claims, and more barrel sales.

The CF barrels are stiff and lightweight and evidently shoot well. Why not leave it at that, rather than adding the false advertising. Because at sustained higher rates of fire, the only scenario where one barrel will materially benefit from more efficient heat transfer above the other, the steel barrel will transfer heat at higher rates, and cool more quickly than the insulated CF wrapped barrel.

 

[5RWill]

Could someone not grab two guns of the same cartridge, load, and barrel contours between the two side by side and put them through say 25rds sustained. I mean surely a steel barrel manufacturer can match the contour of a proof, cut to the same length, reamer, etc. Put a thermal reader on the barrels, if the Proof/Carbon is lower it's obviously insulating the barrel. If it's higher the thermal resin they're using to transfer heat, evidently works, that or the thermal conductivity of the CF used is higher than the steel being used. Maybe it's the thermal conductivity of the resin and it's ability to transfer the heat to the CF that is the reason for their claim? I'm spitballing here so take it with a grain of salt. I remember very little from thermodynamics.

Fact of the matter is outside of the science even if the CF wrap does as claimed, a barrel is a perishable item and at 730$ a pop (1180ish once after smithing) noone in competition is going to be running one and putting it through long rates of fire. I have one on the way despite my skepticism. Of what reviews and claims i could find they evidently shoot great, which is all i want for it on this particular rifle.

It's interesting because i see different claims. Some say they can grab the barrel after a long string of fire. That would be a red flag to me, obviously insulating the barrel. Others say that you need a mirage band for sustained fire that the entire thing will throw up a tone of mirage vs a steel barrel. Which i would think would indicate heat transfer. I've never shot my match gun hot enough to have mirage off the barrel. Suppressor yes, barrel? Nope.

edit
Also found the old hide thread on it from a summer ago.
https://forum.snipershide.com/threads/carbon-wrapped-barrels-heat-dissipation-question.6432004/

 

[Pdvdh]

Just read the SH Thread. Didn't read anything there that undercuts / undermines the content of my Posts above.
I did conclude Lowlight is a marketer for Proof. Must be making some money singing their songs.

If the CF barrels shoot well, don't shift POI as they heat up any worse than a steel barrel, then those are the reasons to own one, if you're looking for a stiff, rigid barrel to reduce rifle weight. To reduce the weight of a carry/backpacking rifle, for example. That would be the tempting value prompting my purchase.
I would not put the CF barrel into repetitive, sustained fire mode, as the steel core is contained in an insulating wrap, which will elevate the bore temp higher than an equivalent contour 100% steel barrel.
But I try to avoid sustained repetitive fire with steel barrels also. So no real difference in use for me there.
CF appears to cost two or more times more than a steel barrel. Only the buyer user can decide if that's good value for their money.
I would never purchase one based on the false advertising claims of cooler temps, which we believe could lead to longer accurate bore life. The thermal conductivity numbers are the best and most appropriate indicator of cooling efficiency, no matter the allegations of thermal diffusivity being bantered about as the more credible intrinsic thermal property of the CF wrap. Ain't so.

 

[5RWill]

Truthfully never known Frank to be on anyone's payroll. He uses them and evidently believes what they showed him. I posted the thread as some more reading on the subject, not necessarily to disprove your post.

I don't really see it anymore at least for the niche i'm in as double the barrel cost. As stupid as it sounds i personally am not going below a 3B for any rifle i have built. I don't like paper thin barrels and am going to shoot suppressed, also don't want the POI changing much if i were to go on a hunt where suppressors aren't legal. Frankly i just like thicker barrels and the aesthetics that follow. So if i would've went with steel it would've been a 3B or 4 fluted. Which is easily 500$, Proof was 730$ still really expensive but i can have my thick barrel and light weight too. Again that's for my circumstance. Blank vs blank it's still double, obviously. I think they need to come down to 630$, i still think 730$ is really high. There was the black friday sell where you could get a cristensen for 400$. Probably would've been worth it.

That said that article Dan linked to talked about heat conductivity varying among different types of carbon fiber composite. Do we have specific thermal conductivity numbers for their carbon fiber? Or are we to assume it's all the same? There were several examples in that article of various types of CF that would best copper.

 

[Pdvdh]

Only I decide what's worth my money. Thank God we all enjoy that right.
I have no thermal conductivity values for Proof's carbon fiber. You'll need nothing more than that value to determine heat transfer efficiency of their carbon wrap. If you obtain it, please share. I'm led to believe the cost of more thermally conductive carbon fiber wraps increases exponentially. Maybe Proof has breached that sound barrier.
Frank didn't provide any evidence, other than he believes. My bet is you'll find Proof advertising on his site. But I don't bet my life on it. He is an overly ardent supporter, offering no evidence other than he believes. I don't believe as no supporting evidence other than personal belief and the want to believe has been provided. Why might that be? Only the folk in possession of that evidence know.

I don't take your Post negatively at all. Appreciated the link to SH. I saw Bryan Litz reportedly tested and reported on CF barrel cooling efficiencies. Nothing remarkable reported by Mr. Litz, according to the posted material. Don't think Bryan has any financial tie to barrel manufacturers.
When your Proof barrel arrives, place it in the chest freezer. After it comes down to freezer temp, hold the barrel by the carbon wrap, and compare it to holding it by the steel chamber. If the steel chamber is less cold to hold, then you've got a winner!

This method of testing doesn't involve cooking the bore with repetitive fire. Such a simple test to settle the matter of CF insulation values.

I found it amusing that CF barrel owners concluded their barrels ran cooler because their CF wrap felt cooler than they expected! Such a great marketing strategy, no matter how flawed the deduction and how erroneous the conclusion. Only after they understood they just provided the opposite evidence do their CF wraps feel hotter to the touch. Go figure...

Same as we all get to decide on the purchase value of CF versus Steel, we all get to choose what we believe about their relative cooling effectiveness. As it should be. Certainly as I prefer it...

 

[5RWill]

Just so happens my brother has an M24 30 cal blank sitting at home, proof should be here tomorrow. When i go home next weekend i'll chunk them in the freezer. As said earlier outside of the intrinsic details of determining whether or not the marketing is true. The proof (pun intended) should be in the pudding.

 

[Pdvdh]

The information provided from the Christensen Arms' engineer stated:
"This means that carbon fiber epoxy parallel to fibers has an approximate thermal diffusivity of 450 times greater than carbon steel and perpendicular is approximately 37 times greater."

Does your CF wrap feel between 37 and 450 times warmer (edit - my bad here) than you've experienced when touching the steel after a string of fire? Does the CF wrap feel 37 to 450 times colder (edit - my bad here) than the steel shank of the barrel out of your chest freezer? [Edit: It doesn't equate to 37 to 450 times warmer or colder temperature. I know they'll come gunning for any miss-steps.] The CF should provide a 37 to 450 times higher rate of heat transfer, if those thermal diffusivity values are an accurate indicator of heat transfer rates. You get the idea... there should be a notable difference in sensed or measured surface temperature.

Why didn't Bryan Litz detect between 37 and 450 times additional heat transfer? That's not a teeny, itsy bitsy difference. Yet Mr. Litz's book did not report any remarkable differences between CF & steel barrels. (I haven't read the book - only the SH Forum posts on the findings reported in the book.)

If there's an incredulous disconnect between thermal diffusivity values and real life experiences on CF wrap heat transfer, could it be that "thermal diffusivity" is a poor term/coefficient for purposes of quantifying the heat transfer property of the carbon fiber wrap?

I don't know the thermal conductivity coefficient of Proof's carbon fiber wrap, just as I didn't know the thermal conductivity coefficient for Christensen Arms CF wrap. Does anyone? Has it ever been published or provided, anywhere? In the midst of the promotional advertising claiming improved thermal efficiencies, does ANYONE know their thermal conductivity value?

This much I do know... If I owned Proof Research, and my carbon fiber wrap transferred heat much better than the competition's carbon fiber wrap, and if it kept the bore much cooler than the competition's CF, I'd be running (not walking) to publish that Thermal Conductivity coefficient value. Promoting this much improved feature of my product, compared to all the competition's products. Is that not the way it works?

The pertinent heat transfer property has not been provided. The evidence is nebulous - a mystery. The claims of improved cooling abound. Yeah, I believe...

 

[Pdvdh]

Just so happens my brother has an M24 30 cal blank sitting at home, proof should be here tomorrow. When i go home next weekend i'll chunk them in the freezer. As said earlier outside of the intrinsic details of determining whether or not the marketing is true. The proof (pun intended) should be in the pudding.

Maybe I'll need some spices to season the crow dinner! Look forward to learning what you're able to determine.