Why use a carbon wrapped barel?

[Pdvdh]

Have at it. I welcome your disagreement. And look forward to your very lengthy rebuttal. After all, what fun is unanimous agreement.
Eventually you'll come to the realization that the answer to the question you asked is dependent upon a variety of variable factors (values) that will need to be run thru laborious mathematical equations. And the results will then only be applicable to your specific input parameter values. Change the outdoor ambient temperature, the number of shots fired, the bore temperature, the steel barrel wall thickness, the CFW thickness, and then start the calculations all over again.

I just identified the single most meaningful value for purposes of putting the matter to rest. And you blew right past it. So I won't be your source of a satisfactory answer.

THERMAL CONDUCTIVITY COEFFICIENT.

I'm not screaming. The caps are there in case you didn't catch it in the multiple prior posts from several different knowledgeable, practicing engineers. If you did catch it, then your understanding of basic heat transfer principles is lacking at this time. Indeed, you will need to figure it out your own way. Excellent, and I welcome your research. Look forward to your settling this matter, once and for all, when you post the conclusions of your efforts.

 

[Mram10us]

Have at it. I welcome your disagreement. And look forward to your very lengthy rebuttal. After all, what fun is unanimous agreement.
Eventually you'll come to the realization that the answer to the question you asked is dependent upon a variety of variable factors (values) that will need to be run thru laborious mathematical equations. And the results will then only be applicable to your specific input parameter values. Change the outdoor ambient temperature, the number of shots fired, the bore temperature, the steel barrel wall thickness, the CFW thickness, and then start the calculations all over again.

I just identified the single most meaningful value for purposes of putting the matter to rest. And you blew right past it. So I won't be your source of a satisfactory answer.

THERMAL CONDUCTIVITY COEFFICIENT.

I'm not screaming. The caps are there in case you didn't catch it in the multiple prior posts from several different knowledgeable, practicing engineers. If you did catch it, then your understanding of basic heat transfer principles is lacking at this time. Indeed, you will need to figure it out your own way. Excellent, and I welcome your research. Look forward to your settling this matter, once and for all, when you post the conclusions of your efforts.

If you are an engineer, why can't you run these numbers? What did I miss in your post that was "single most meaningful value"? Without numbers to back our positions, it is a waste of time. If it is your profession, why won't you post numbers. I have given volumes. What else do you need from me to run these formulas?

 

[UniqueUserName]

If you are an engineer, why can't you run these numbers? What did I miss in your post that was "single most meaningful value"? Without numbers to back our positions, it is a waste of time. If it is your profession, why won't you post numbers. I have given volumes. What else do you need from me to run these formulas?

What good are volumes without dimensions; bore diameter; liner thickness; specific barrel and liner material compositions; specific CF composite formula; composite thickness; thermal conductivity coefficients for each specific material, compound (directional for the CF), and bonding agent; circumference/material thickness at intervals along the barrel; fluting depth, width and profile; surface emissivity (based on materials, coatings, finish texture); ambient temperature, humidity, air density, air velocity and direction relative to the firearm; stock material; space between barrel and stock at intervals along the common length; Amount of thermal energy to be imparted to the bore, number of iterations, intervals between iterations; breech open time between iterations; breech state (open or closed) during the idle cool-down period; relevant measurement points (bore surface? barrel surface? mid-thickness? at what points along the length of the barrel?; Maximum acceptable temperature at each point for each barrel (how hot is too hot)?

These are but a few variables to be defined and incorporated into the cooling model for each barrel/firearm variant. I'm sure I have omitted at least as may as I have enumerated. If you think that modeling the cooling process in terms of a time/temperature scale is a simple formulaic expression, I think you underestimate the complexity and number of factors involved. I'm certainly not capable of creating the model, even if all of the variables were defined. In this instance, I know enough to be aware of what I don't know.

I can tell you with confidence that the single overriding factor is migrating heat away from the bore (the greater thermal conductivity and thermal capacity win), then, secondarily, dispersing that heat from the inner and outer surfaces of the barrel via the combination of radiation, convection and to some degree conduction.

Given that we can be confident that barrel steel will have substantially greater thermal conductivity than a graphite/resin composite, we can reasonably postulate that under any normal conditions the steel barrel will conduct heat away from the bore more rapidly than the CF wrapped barrel.

If you want someone to build a model to prove it true/false and to what degree, it appears that burden falls back to you. If you can't define the control variables and how they relate, you can't build the model or define a practical test.

 

[Pdvdh]

If you are an engineer, why can't you run these numbers? What did I miss in your post that was "single most meaningful value"? Without numbers to back our positions, it is a waste of time. If it is your profession, why won't you post numbers. I have given volumes. What else do you need from me to run these formulas?

If you were an engineer with a heat transfer background, you wouldn't have asked those questions.

For the rest of the readership, now you have some idea why a barrel manufacturer can claim superlative barrel cooling properties. It's a relatively safe gamble on their part because the majority of their customers have no easy way to conveniently disprove the propaganda. And when you touch the barrel after a string of shots, carbon fiber will feel cooler to the touch than a steel barrel. It seems so obvious based on touch, that it must be true. The majority of the reports from the 'believers' on this forum used to state "cooler to the touch" to justify their belief their CFW barrels shot cooler than their steel barrels. UNTIL I explained their cool exterior barrel surface was actually evidence their CFW was insulating the steel inner sleeve of their CFW barrel. But you'll still find that reverse logic explanation crop up on the Forum fairly regularly.

Why did some bullet manufacturers inflate the BC values of their bullets before their customers had access to accurate, affordable bullet measuring instruments? Because they could get away with it, and coincidentally, it increased company profits. Their bullets were simply better than the competitions' bullets. Their marketing sections are without shame, and the culprits receive financial reward.

One reason my last two CFW barrel purchases are manufactured by Bartlein. Haven't seen them advertising their CFW barrels run as cool as dry ice.

 

[DJ Fergus]

[QUOTE="phorwath, post: 2071658, member: 4191"

the heat remains in the steel liner core for a longer period of time.
[/QUOTE]
I agree with you about the core remaining hotter for longer. I happen to get significantly more scope mirage from my CF barrel more so than any other of my barrels. I've tried different scopes with the same results.
As far as balance, I've had two rifles with 3B contour fluted barrels. Although I know there is a slight difference vs the CF barrel, I really can't perceive much difference from a prone shooting position from a balance standpoint. I do prefer just a bit more weight on the barrel end of the rifle than the butt end. I don't particularly like more weight on the butt end than the barrel end.

 

[JAYgs8163]

I've said this a couple of times before but I will post it once more. I run CF for one reason only, weight reduction on a heavier profile barrel for hunting purposes that I can still run suppressed. I think most of us here have purchased them for weight reduction. Personally, I never purchased my CF barrels for faster cooling.

I have begun 2 new projects though of building short action, shorter barreled hunting rifles, using faster cartridges but using steel barrels. One will be a 18" barrel 300WSM in a lighter varmint profile but fluted, the other a 20" fluted lighter varmint profile Krieger barrel in 6 Creedmoor. If everything comes out right the weight will be close to my CF rigs. Based on my calcs both rifles will come in between 6.5-6.75 pounds depending on bedding materials and other minor inletting items.

 

[DJ Fergus]

I'm not necessarily arguing for or against CF wrapped barrels. I can see what they offer. What I don't understand is when someone has a carbon fiber barrel but didn't go with a light weight stock when there were lighter alternatives and then they mount an optic to it that weighs somewhere in the neighborhood of 30 to 40 ounces. Which ends up making that rifle heavier on the rear end. If lighter is the goal, then I'm not going to trade off barrel weight so I can go with a heavier stock and optic.

Now saying all of that, I do see where a cf barrel would be beneficial running a supressor. But if I'm going for an ultimate light weight, long mountain country hiking rifle , I would be trying to find a way not to incorporate a supresor into that build.

 

[Mram10us]

What good are volumes without dimensions; bore diameter; liner thickness; specific barrel and liner material compositions; specific CF composite formula; composite thickness; thermal conductivity coefficients for each specific material, compound (directional for the CF), and bonding agent; circumference/material thickness at intervals along the barrel; fluting depth, width and profile; surface emissivity (based on materials, coatings, finish texture); ambient temperature, humidity, air density, air velocity and direction relative to the firearm; stock material; space between barrel and stock at intervals along the common length; Amount of thermal energy to be imparted to the bore, number of iterations, intervals between iterations; breech open time between iterations; breech state (open or closed) during the idle cool-down period; relevant measurement points (bore surface? barrel surface? mid-thickness? at what points along the length of the barrel?; Maximum acceptable temperature at each point for each barrel (how hot is too hot)?

These are but a few variables to be defined and incorporated into the cooling model for each barrel/firearm variant. I'm sure I have omitted at least as may as I have enumerated. If you think that modeling the cooling process in terms of a time/temperature scale is a simple formulaic expression, I think you underestimate the complexity and number of factors involved. I'm certainly not capable of creating the model, even if all of the variables were defined. In this instance, I know enough to be aware of what I don't know.

I can tell you with confidence that the single overriding factor is migrating heat away from the bore (the greater thermal conductivity and thermal capacity win), then, secondarily, dispersing that heat from the inner and outer surfaces of the barrel via the combination of radiation, convection and to some degree conduction.

Given that we can be confident that barrel steel will have substantially greater thermal conductivity than a graphite/resin composite, we can reasonably postulate that under any normal conditions the steel barrel will conduct heat away from the bore more rapidly than the CF wrapped barrel.

If you want someone to build a model to prove it true/false and to what degree, it appears that burden falls back to you. If you can't define the control variables and how they relate, you can't build the model or define a practical test.

Burden of what? I am asking the question based on no experience in thermal modeling. You said a lot in your post and explain that you understand this area much more than me, but want to make this an argument rather than just putting some simple numbers to the volumes I've given. If you don't know how to run the numbers, fine, neither do I, but I will learn

 

[Mram10us]

If you were an engineer with a heat transfer background, you wouldn't have asked those questions.

For the rest of the readership, now you have some idea why a barrel manufacturer can claim superlative barrel cooling properties. It's a relatively safe gamble on their part because the majority of their customers have no easy way to conveniently disprove the propaganda. And when you touch the barrel after a string of shots, carbon fiber will feel cooler to the touch than a steel barrel. It seems so obvious based on touch, that it must be true. The majority of the reports from the 'believers' on this forum used to state "cooler to the touch" to justify their belief their CFW barrels shot cooler than their steel barrels. UNTIL I explained their cool exterior barrel surface was actually evidence their CFW was insulating the steel inner sleeve of their CFW barrel. But you'll still find that reverse logic explanation crop up on the Forum fairly regularly.

Why did some bullet manufacturers inflate the BC values of their bullets before their customers had access to accurate, affordable bullet measuring instruments? Because they could get away with it, and coincidentally, it increased company profits. Their bullets were simply better than the competitions' bullets. Their marketing sections are without shame, and the culprits receive financial reward.

One reason my last two CFW barrel purchases are manufactured by Bartlein. Haven't seen them advertising their CFW barrels run as cool as dry ice.

Of course I don't have a background in this, which i've stated. I am asking any engineer that knows how, to run the numbers with the associated volumes. I can get whatever variables needed to help out since there are so many thermal variables with different epoxies, etc. Again, you have stated your'e an expert, but are not willing to run any number for us to help explain. It isn't an argument, it is a problem that needs solved.

 

[DJ Fergus]

I guess my mail reason that I won't go back with another CF wrapped barrel is the issue with the scope mirage it generates most of the time. I get one, sometimes two shots and I have to wait for a while for the mirage to go away. This is with a 7mm magnum. I've heard that it's not as bad with CF barrels in standard non magnum chamberings.

 

[tacomHQ]

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

Thank you for the question: this is not combative in the least.
Setting the stage:
.338cal x 30L x 1.45dia has 394% greater surface area on our barrels than its equivalent weight 1.1" diameter solid barrel. It is also at least 56% stiffer plus the "vibration" is specifically directional- the direction we want it to move.
The airflow event takes place during firing in two stages:

1) At ignition and bullet travel down the barrel a column of air (bore diameter/column) is moving out of the muzzle at 3100fps (I shoot a 33XC 285A-tip) that movement thru the muzzle creates a low pressure zone.
The barrels have ports at the rear of the channels. The low pressure zone presented at the muzzle end pulls air thru the channels at a fairly high velocity. High velocity air typically runs cooler than ambient (venturi). The velocity is so high that we have found 8 little piles of dust/debris impacted on the back of brakes during a shooting event.
2) As the bullet leaves an overpressure occurs pushing air back down the channels. You will see "wisp" of powder smoke curl out of the ports during a shooting event.

Therefore air is changed twice during one round.

We also calculate the areas of the webbing to be as "thin" as reasonably possible. I don't believe heat transfer is totally linear and increases as the mass decreases- or in the simple example thickness. A 1/4" thick piece will accept heat and transfer it differently than a 1/8" pc and certainly different than a .04" piece. Radiators. The surface area is increasing faster than the mass is decreasing as a ratio. Simplistically speaking. Inversely surface area reduces at a cube+ versus increase in mass as things get big (Simplistically). Elephants.

Our barrels run cooler - fact.
They are giant heat sinks- fact.
Air moves thru the interior- fact. Solution to pollution is dilution- Or heat in this case.
The chamber runs cooler than the barrel- fact. The heat sink is in front of the chamber. Energy wants balance.
Multiple third parties are noting an increased barrel life.
Our barrels will rise in temp for a minute or two after a typical long string and then start cooling. They will reach ambient in a fraction of the time a standard barrel does.
On a typical 65-70 degree day shooting our 300 Norma under normal "range day" fun- it won't heat up for tens of rounds- if at all. Our .375 Cheytac after 15 rounds on a stage can be picked up by the barrel. Most likely is already going down in temperature by the time you get back to your staging area.

 

[Mram10us]

Thank you for the question: this is not combative in the least.
Setting the stage:
.338cal x 30L x 1.45dia has 394% greater surface area on our barrels than its equivalent weight 1.1" diameter solid barrel. It is also at least 56% stiffer plus the "vibration" is specifically directional- the direction we want it to move.
The airflow event takes place during firing in two stages:

1) At ignition and bullet travel down the barrel a column of air (bore diameter/column) is moving out of the muzzle at 3100fps (I shoot a 33XC 285A-tip) that movement thru the muzzle creates a low pressure zone.
The barrels have ports at the rear of the channels. The low pressure zone presented at the muzzle end pulls air thru the channels at a fairly high velocity. High velocity air typically runs cooler than ambient (venturi). The velocity is so high that we have found 8 little piles of dust/debris impacted on the back of brakes during a shooting event.
2) As the bullet leaves an overpressure occurs pushing air back down the channels. You will see "wisp" of powder smoke curl out of the ports during a shooting event.

Therefore air is changed twice during one round.

We also calculate the areas of the webbing to be as "thin" as reasonably possible. I don't believe heat transfer is totally linear and increases as the mass decreases- or in the simple example thickness. A 1/4" thick piece will accept heat and transfer it differently than a 1/8" pc and certainly different than a .04" piece. Radiators. The surface area is increasing faster than the mass is decreasing as a ratio. Simplistically speaking. Inversely surface area reduces at a cube+ versus increase in mass as things get big (Simplistically). Elephants.

Our barrels run cooler - fact.
They are giant heat sinks- fact.
Air moves thru the interior- fact. Solution to pollution is dilution- Or heat in this case.
The chamber runs cooler than the barrel- fact. The heat sink is in front of the chamber. Energy wants balance.
Multiple third parties are noting an increased barrel life.
Our barrels will rise in temp for a minute or two after a typical long string and then start cooling. They will reach ambient in a fraction of the time a standard barrel does.
On a typical 65-70 degree day shooting our 300 Norma under normal "range day" fun- it won't heat up for tens of rounds- if at all. Our .375 Cheytac after 15 rounds on a stage can be picked up by the barrel. Most likely is already going down in temperature by the time you get back to your staging area.

Love the innovation and design.

 

[CHAGA50]

I wish more weights would be published. One can find weight calculators online but hard to find someone that will say exactly what said barrel will weigh.

My 338 barrel , 34" aol , shank 1.37 , 5" chamber , muzzle 0.800 , about 8.5 pounds

 

[Pdvdh]

Do I have any obligation? You're asking someone to invest countless hours to generate an incredibly complex algorithum (mathematical model) to satisfy your personal curiousity.

Research the Thermal Conductivity Coefficient for the carbon fiber wrap media the barrel manufacturer is using, and compare it to the Thermal Conductivity Coefficient for steel barrels. The generic, one-size-fits-all answer to your curiousity is, "The barrel material with the higher Thermal Conductivity Coefficient will transfer heat at the higher rate. Which is the same as saying, it will cool down (shed heat) at a faster rate.

Your problem will be, no carbon barrel manufacturer employee will provide the value for their CFW, unless that employee wants fired. Because that value will burst the perpetual propaganda bubble.

If you wanna spend your time and money satisfying a curiousity, I'd suggest purchasing equipment that will reliably measure the temperature of the bore in your CFW and a 100% steel barrel of identical size. Shoot the exact same cartridge and ammunition in each of the two identically shaped barrels, at the same rate of fire, under the same outdoor temperatures, at the same location and time, with no wind, and both barrels either in broad sunlight, or under shade. Place the temperature sensor in the bore immediately after firing a string of rounds down both barrels. The temperature sensor will need to be placed identically in both bores, and never be moved as the temperatures are being collected. It would be ideal if the temperature sensor wasn't in direct contact with the steel bore, but was held centered in the bore with an air gap circumferally surrounding the sensor. Monitor and record the bore temperatures versus time. Keep everything as apples to apples as possible, meaning control all temperature affecting influences. Measure and compare bore temperatures over time and voila, you will have demonstrated with empirical temperature data collected over time, which barrel cooled down quicker (transfered heat out from the bore at the faster rate).

It would be ideal to have two temperature sensors recording the rate of bore cool down in both barrels at the same time. And then perform a second test swapping the temperature sensing equipment between barrels and documenting the same result. In other words, strive for a well controlled test, in the effort to yield the most equally comparable and defendable temperature data.