Why use a carbon wrapped barel?

[25WSM]

How do you set back a cf barrel 6 or 7 times? I do 4 on my br barrels and they have twice the shank length. I loose 2 inches doing it 4 times. Then they go on hunting guns.
Shep

 

[JAYgs8163]

They don't make CF barrels in that light contour of a profile and if they did they would be lighter weight. If comparing apples to apples with the same length and profile from steel to CF wrapped the CF is always going to significantly lighter. Usually 35-45% lighter.

 

[UniqueUserName]

I'm a mechanical engineer and I build rockets for a living my guy. Never seen a low thermal conductivity heat sink but go on ahead and act like citing a "classified" study is a legitimate reference. I think the claim with CF barrels cooling more efficiently or more quickly can both be true and misleading. The greater the temperature difference from atmospheric conditions the more "efficiently" something will cool down and the more "quickly" it will cool down. I'm sure you were thinking about Newton's law of cooling when you typed all this up.

As a Level-III thermographer, I agree with what you are saying. To cool a barrel, heat must be transferred from the bore to the surface via thermal conduction. Steel is a much better thermal conductor than carbon fiber, especially when the heat must travel transverse to the fiber. Once heat is conducted to the surface it is dissipated via radiation and convection (some via conduction into the stock/chassis where there is contact). Carbon fiber has a greater emissivity than most steel surfaces so once heat makes its way to the surface it will radiate more rapidly.

Carbon fiber will provide a cooler surface temperature for both reasons listed above, but that has absolutely no bearing on bore temperature, which is what matters. If one wants to know how effective each type is at cooling, they must measure bore temp, not surface temp. I too would like to see this fantastical, "classified" study and hear the details of exactly what "physics" this person is employing in his analysis.

P.S. I have a hunting rifle with a carbon fiber wrapped barrel and like it plenty, but it's not the one I would choose for sustained rate of fire if I wanted it to last. I like both steel and CF wrapped, but each has its own advantages and disadvantages, based on application.

 

[rustyshackleford]

Sweet! I'd love to pick your brain. Is thermal conductivity based on meterial thickness, weight or what? Having a hard time getting that part answered. In other words, if I have an inch of steel or an inch of steel, the TC is as listed? Also, we are assuming standard epoxy resin, not silver or graphite additives.

So thermal conductivity is dependent on the material itself and independent of quantity if that's what you are asking. Depending on resin and additives you could have higher or lower thermal conductivity than baseline epoxy. So in order to cool the barrel faster than steel you either have to have a higher thermal conductivity or have geometry matching the critical radius of insulation. Basically you CAN cool something off by wrapping it in a an insulator depending on the thermal conductivity of the materials, temperature differences, and size constraints. Using critical radius of an insulator would make perfect sense but I've never seen anyone refer to it in these discussions or by the mfg so I'm assuming it's not the mechanism at work here.

I have read what another poster said about transmitting heat longitudinally along the fibers but then you'd lose your rigidity. Basically I think CF does give you the rigidity they claim it does, but to be configured for the property of rigidity it's also arranged in a manner that certainly seems like it would insulate the barrel. I think it's fine for slower volumes of fire but I don't believe it dissipates heat in a better way than steel that translates to longer barrel life. I'm with the other posters here who are of the mind to run a steel barrel of a slightly smaller diameter and flute it if barrel life is any concern.

 

[Betarider]

The 2 I own are built to hunt long distance (as in hikes)and I know for a fact they cool faster at the range during load development.
Yep, they are cool and I also own 2 6.5 Creedmoors .

That disapating the heat thing is pretty
The fat target barrel qualities without the weight is cool the high price isn't that cool but accuracy is priceless so my new gun has one and it shoots as cool as it looks

 

[bdyal1972]

I'm a mechanical engineer and I build rockets for a living my guy. Never seen a low thermal conductivity heat sink but go on ahead and act like citing a "classified" study is a legitimate reference. I think the claim with CF barrels cooling more efficiently or more quickly can both be true and misleading. The greater the temperature difference from atmospheric conditions the more "efficiently" something will cool down and the more "quickly" it will cool down. I'm sure you were thinking about Newton's law of cooling when you typed all this up.

Sir I was not even 20 when I FIRST understood this technology....

That was in the days of DOS.

28 years later it is proven technology...

As clint east wood said in "space cowboys"

"I suggest you back to your college and get your money back!"

Btw I was part of a patent in the early 90s using carbon fiber to extract temps from steam potatoe peelers designed in the 50s....

Think 3 dimensional

If you can't see 3 dimensional in your mind I am sorry...

If the wrap is 30" wide-10 micron thick and 30 meters long....

How much surface area is their on a 30" long 1" diameter barrel?????

Its a toilet paper dispenser the barrel is the tube.....

Best answer i can give you buddy...

The technology was PROVEN almost 30 years ago.....

Period.....

If you CAN NOT GRASP IT IS INCONSEQUENTIAL AND UNIMPORTANT....

I doubt pushrods in 20000rpm motors would be in there if heat was an issue

Same for airborne cannons

M4s

Helicopter rotors

50 cal antimaterial rifles

90% of 10-10-1000 competitor rifles...

Cf wrapped barrels CAN BE lighter-longer-larger diameter-cool faster-have longer rifling life-maintain accuracy longer maintain velocity longer

Than

All steel barrels

Of the same quality and construction

At

The same weight

AND

a higher price

 

[bdyal1972]

How do you set back a cf barrel 6 or 7 times? I do 4 on my br barrels and they have twice the shank length. I loose 2 inches doing it 4 times. Then they go on hunting guns.
Shep

The ones I see like that are 5" + shank length heavy bullet slow twist sllooowwww powders (slower than retumbo) setback approximately 1/2" each rechambering then fire lapped

Btw thanks shep

A few were gain twist as well

3 were an experiment in electro hardening the chamber/throat....

Those were special but not time/$ viable for ANYONE outside the military...

 

[George Dean]

For the same reason that you put a spoiler and fart can muffler a Honda Civic.

Segue alert: I'd like to shove a potato up the exhaust of those annoying little cars that sound like an over wound toy airplane! Reminds me of the times, as a child, we used clothespins to put playing cards in the spokes of our bikes.

 

[Betarider]

As a Level-III thermographer, I agree with what you are saying. To cool a barrel, heat must be transferred from the bore to the surface via thermal conduction. Steel is a much better thermal conductor than carbon fiber, especially when the heat must travel transverse to the fiber. Once heat is conducted to the surface it is dissipated via radiation and convection (some via conduction into the stock/chassis where there is contact). Carbon fiber has a greater emissivity than most steel surfaces so once heat makes its way to the surface it will radiate more rapidly.

Carbon fiber will provide a cooler surface temperature for both reasons listed above, but that has absolutely no bearing on bore temperature, which is what matters. If one wants to know how effective each type is at cooling, they must measure bore temp, not surface temp. I too would like to see this fantastical, "classified" study and hear the details of exactly what "physics" this person is employing in his analysis.

P.S. I have a hunting rifle with a carbon fiber wrapped barrel and like it plenty, but it's not the one I would choose for sustained rate of fire if I wanted it to last. I like both steel and CF wrapped, but each has its own advantages and disadvantages, based on application.

I'm just a farmer so maybe I look at things differently? But a fat piece of metal will hold heat,ei heat sink. But a thin piece is like a cooling fin disapating the heat. Agreed. So the core of the barrel is much thinner than standard steel ones. Now the part I don't know is what happens to the heat. Does it cool from the inside faster since it's wrapped in a blanket??

 

[UniqueUserName]

I'm just a farmer so maybe I look at things differently? But a fat piece of metal will hold heat,ei heat sink. But a thin piece is like a cooling fin disapating the heat. Agreed. So the core of the barrel is much thinner than standard steel ones. Now the part I don't know is what happens to the heat. Does it cool from the inside faster since it's wrapped in a blanket??

A fat piece of metal will have greater thermal capacitance. It will absorb a greater amount of thermal energy to reach a given temperature and tend to hold it longer. If you put the same amount of thermal energy into a smaller mass of the same material, it's going to get a lot hotter, faster and will tend to cool faster because of the greater temperature differential and the lesser ratio of mass to surface area. It's the peak temp that's going to destroy things. Now if you take that skinny tube, wrap an insulating blanket around it and dump the same amount of thermal energy into it, it's still going to get very hot, but now it will cool much more slowly due to the reduced rate of thermal transfer through the insulator. It's going to have a much lower surface temp because of the slower thermal transfer, but it's going to be much hotter and stay hotter, longer at the bore. But yes, starting at a given temperature a skinnier piece of steel will lose heat more rapidly than a fat piece of steel, but the fat piece of steel will absorb a much greater amount of thermal energy before it reaches the same temp as the smaller piece of steel.

BTW: I know enough about farming to know that it requires a lot of smarts to be successful at it.

 

[Rhino55]

Gentlemen Can we agree to disagree? This has turned into a contest with no winners because everyone is talking pass each other. A fluted barrel has more surface area for heat to dissipate faster and a CF barrel is thinner Steel core so it won't retain or store heat.

 

[Betarider]

this forum emphasizes hunting more so then BR - I doubt any one of us will be grabbing our f-class rifle to take hunting, so why use that as a comparison here?

I agree with you if it gave an advantage to them they would be using it.

 

[HuntnPack]

 

[Rich Coyle]

A couple years ago I did two 6.5 mm rifles. One on the twenty-six ounce six lug Mark V Weatherby action using a 26" heavily fluted .550" muzzle steel barrel. The other was a 26" carbon fiber .850"muzzle barrel on a Pierce titanium action. Both barrels looked really cool to me and both weighed forty ounces. The Weatherby fired groups about 5/8" for three shots and up to 15/16" for five shots. The Pierce fired 1 1/2" for three shots on a good day. The Weatherby had a wildcat that matched a .264 Win Mag without the belt. Velocity with Hammer Shockhammer 130 averaged 3,190 feet per second. The Pierce used a .338 RUM chamber but .300 RUM brass to get a .100" longer neck. While I was at it I did a Lilja 28" 9 twist barrel on my son-in-law's Savage. It fired Nosler 140 Accubonds at 3,419 feet per second and did five shots around 3/4". By the way, Son John took one of my Bushnell 6500 4 1/2-30X50's for his Savage. Now I have only two. The other is on the .375 wildcat.

For reference the Weatherby had a Swarovski z5 5-25X52. The Pierce had a Leupold VX-6 4-24X52. The Swarovski went back for service twice in about eighteen months. The Leupold never gave any trouble. The Pierce rifle was disassembled and parts sold; including the scope. The Swarovski was sold with full disclosure about its history and replaced with a Bushnell 6500 4 1/2-30X50.