Proof Carbon Barrel Cooling

[Deane]

I've worked as wea pipe welder and an inspector for piping and structural steel fabrication/welding. Some steels need preheat, post weld stress relief, and sometimes we used heat to straighten or form steel. In most cases forced cooling with ambient air is allowed when the steel reaches 600f or cooler.

I'm no metallurgist so I can't give a technical explanation why.

 

[coyotezapper]

I'm still trying to sort out this new barrel. I tried something this weekend that seems to work really well, but just wondering if my good idea might not be. Asking to see if anyone knows. It is a 28 Nosler. 3 shots and it is really hot inside and seems not to cool at all in a reasonably amount of time. I went to Academy Sports and bought a high volume fan meant to blow up air mattresses and such. It uses 6 "C" cell batteries. Added a couple of feet of clear vinyl tubing that fits tight in the chamber. It really blows hard and will cool the barrel from the inside in about 2 minutes. Seems to work really well and using ambient air temperature to cool. Question is, is there any danger to the barrel cooling it this quickly? One thing is for sure, it is cheap and seems to work really well.

Bryan Litz did a test with carbon barrels and found out that carbon barrels heat slower but also cool slower than conventional steel barrels.

 

[Smokenaces]

I have a small cheap dedicated rifle barrel shop vac that I place the tube over the muzzle and open the bolt. Suck the heat out in nothing flat.

 

[ntsqd]

Deane, in your case the steel has cooled below it's lowest phase transition temperature. You can mildly affect the tempering of the HAZ, but you're not going to harden it by cooling it fast below that temperature.

That a carbon wrapped barrel cools slower isn't a surprise as I've suspected that the carbon tube has a lower thermal transfer than metals. That it heats slower was a surprise until I thought about it. Suspect that we're talking about the surface temperature, which would be the carbon tube surface temperature and not the steel surface temperature. So it makes sense that the carbon tube is a thermal insulator. It is slow to heat up and it is slow to cool down.

 

[Buzzsaw]

does blowing 100* ambient air through a barrel, really cool it??? I have both tools mentioned above and love them but a guy asked me this the other day, i didnt have an answer.

I think the minnow bucket aerator would work good too

 

[ntsqd]

It is a non-linear relationship. If the barrel is 500°f and you blow 100°f air thru it, its going to cool fairly fast. If the barrel is 300°f and you blow 100°f air thru it its going to cool, but at a slower rate. If the barrel is 110°f and you blow 100°f air thru it its still going to cool, but at a very slow rate.

With all things thermal "The more radical the temperature difference, the more radical the reaction."
Cold water poured into a Styrofoam cup full of R-12 refrigerant makes the coolest looking ice sculpture.
Boiling hot water poured into a Styrofoam cup full of R-12 refrigerant blows the cup apart & vaporizes all of the water.
Wanna ask how I know this?

 

[Buzzsaw]

never was good at science or physics but you make sense. thanks

 

[tacomHQ]

A daily fan of this site and always quite insightful.
To those who do not know us - TACOMHQ- along with long range optics we produce a type of barrel. It is not in competition with Proof or any wrapped barrel. It is not a light weight barrel and certainly not a mountain gun. However, if a barrel 32 inches long that starts at a weight of 6.2 pounds, is pound for pound significantly stiffer, well over 300% more cooling surface interest you -look us up. Our 300NM does not show heat signs until well into the deep teens in a shooting string, cools very rapidly, shows consistently less group drift, less SD drift than standard barrels... and longer life. You will see the only existing videos of complex computer simulations of a barrel whip and vibration. While we are typically known in ELR for our optics, teams are well into testing of our barrels along with 3rd party load development people and all - all - to date have noted that our barrels are an outstanding product. "The real deal" per Cal and Precision Rifle Blog (see video). You will also find our recoil event is different/less due to reduced vibration/whip. This was recently highlighted at K2M by a shooter running the exact same gun (.375 Cheytac- free fired/no shoulder contact) with the only difference being the barrel. Since it is a heat sink this same shooter (see video) was shocked at how cool the gun ran: in 10 shots the barrel raised from 72deg to 86deg as the high. At a recent Sniper Forum in Colorado are shot strings consistently ran 20-40rds with barrel temps being 10deg above ambient soak (Frank at Snipers Hide) with ambient static soak of 110deg and 117deg after the shot strings. A different technology. A different direction.

 

[Orange Dust]

All I know is you can shoot this thing (proof barreled 28 Nosler) three times, plug the gizmo I built in the chamber and the thing blows air out the muzzle hot enough to burn your hand. Wait a minute or two and the air feels cool. Somewhere I have a Infrared thermometer. I'm going to dig it out and see what the temp of the air is when I hook it up after three shots, and see how long it takes for the air to reach ambient temperature. Should be an interesting experiment. I will get back with you all after I shoot it again this weekend.

 

[ntsqd]

never was good at science or physics but you make sense. thanks

Good! and thank you too. My industrial tech instructor was good at visual demonstrations of physics stuff. Sometime I'll have to post what he showed us in the welding portion of that class......

All I know is you can shoot this thing (proof barreled 28 Nosler) three times, plug the gizmo I built in the chamber and the thing blows air out the muzzle hot enough to burn your hand. Wait a minute or two and the air feels cool. Somewhere I have a Infrared thermometer. I'm going to dig it out and see what the temp of the air is when I hook it up after three shots, and see how long it takes for the air to reach ambient temperature. Should be an interesting experiment. I will get back with you all after I shoot it again this weekend.

I'm interested in those results. Would be interesting to see what the temperature difference in the exposed barrel steel vs. the carbon tube are too. There's an emissivity difference there, so the color of the steel will slightly skew that number (unless you're willing to put a spot of flat black paint on each!), but it would still be interesting to know.

 

[Orange Dust]

A daily fan of this site and always quite insightful.
To those who do not know us - TACOMHQ- along with long range optics we produce a type of barrel. It is not in competition with Proof or any wrapped barrel. It is not a light weight barrel and certainly not a mountain gun. However, if a barrel 32 inches long that starts at a weight of 6.2 pounds, is pound for pound significantly stiffer, well over 300% more cooling surface interest you -look us up. Our 300NM does not show heat signs until well into the deep teens in a shooting string, cools very rapidly, shows consistently less group drift, less SD drift than standard barrels... and longer life. You will see the only existing videos of complex computer simulations of a barrel whip and vibration. While we are typically known in ELR for our optics, teams are well into testing of our barrels along with 3rd party load development people and all - all - to date have noted that our barrels are an outstanding product. "The real deal" per Cal and Precision Rifle Blog (see video). You will also find our recoil event is different/less due to reduced vibration/whip. This was recently highlighted at K2M by a shooter running the exact same gun (.375 Cheytac- free fired/no shoulder contact) with the only difference being the barrel. Since it is a heat sink this same shooter (see video) was shocked at how cool the gun ran: in 10 shots the barrel raised from 72deg to 86deg as the high. At a recent Sniper Forum in Colorado are shot strings consistently ran 20-40rds with barrel temps being 10deg above ambient soak (Frank at Snipers Hide) with ambient static soak of 110deg and 117deg after the shot strings. A different technology. A different direction.

Really cool stuff. Wish there was a club around here that shot ELR. I would really like to get into it. Then on second thoughts, my wife would divorce me for starting another passion.....

 

[tacomHQ]

Wives and girl friends- gun guys are like car guys. It was on sale, I traded something, the house VISA and the TOY VISA, the stash account, it actually only cost this much, she can't tell the difference between a Model 70 and a Ruger Precision... With my luck a top female shooter is reading this... However, gains really show at the 300cal and up but also shows up in the 6mm territory. Another advantage to reduced harmonics is the reduced load time to find something that shoots well. Our barrels are very forgiving.

 

[Zymurgist]

I posting about barrel thermals on another thread. This is what goes on in Carbon Fiber (CF) barrels:

Heat always transfers from hot to cold through a process physicists call entropy. The heat originates from the hot bore and transfers to the cooler external surface of a steel barrel.

Steel (and other metals) conduct heat through the free electrons present in the iron atoms. As the steel heats up these electrons increasingly vibrate and collide with nearby electrons. These nearby electrons increase their vibrations which excite more electrons and so on.

A material's ability to conduct heat can be measured, steel is around 50 watts per metre-kelvin. High carbon content carbon fiber, from one end of the fiber to the other, is 500W/mK. Wow! That's great! Tens times more heat conduction than steel. But alas, there's more to this.

Looking at the one manufacturers CF barrels, they are laid up with the fiber running from muzzle to breach and back again but that is not the path the heat takes. In order to take advantage of the superior performance of CF you would have to lay up the CF with the fibers running from the steel bore core to the surface.

So what is the thermal coefficient going across the weave and resin of a CF barrel? I found data that says it's anywhere from less than 1W/mK to 5W/mk. The latter is for a resin that has metal powder mixed in it to improve thermal performance. So, CF across the weave is not a very good conductor of heat and that is why the CF barrel stays hot.

Would I use a CF barrel in a hunting rifle? Yes, if it produces the accuracy I want. Would i use one in a high capacity auto loader? Probably not a good idea.

Comment: So the CF in this case is more of an insulator, trapping the heat in the steel barrel ?

Yes, CF acts like an insulator compared to steel. It does trap heat in the barrel as it doesn't allow it to dissipate into the atmosphere as efficiently as steel does. Styrofoam has around 0.03W/mK thermal coefficient. I'd call styrofoam an insulator.

A CF barrel has less Thermal Mass than an all steel barrel and this causes it to have less Specific Heat Capacity than the steel barrel. As a result of that and the fact the heat cannot escape as quickly, the temperature of the CF bore core will rise higher and faster than the bore of an all steel barrel given the same loading and tempo of fire.

Some people on this website have suggested having a fan blow on the barrel to help cool it. I think it would be more effective to blow cooling air through the bore. Water would be a much more efficient bore coolant but I'd be very hesitant to use it as it could cause thermal shock to the barrel and damage it. Depending on how hot the barrel is you might even get scalded by the steam.

Comment: This may come as a surprise but there are many guys, even well decorated BR shooters that cool their barrels with water while out prairie dog shooting. I have never done it but I have seen it work, push a patch thru then back to shooting, very accurately.

That is a great idea. Water has a very high heat of vaporization and even a little bit of it will remove a lot of heat when it turns into steam.

 

[338 dude]

I'm still trying to sort out this new barrel. I tried something this weekend that seems to work really well, but just wondering if my good idea might not be. Asking to see if anyone knows. It is a 28 Nosler. 3 shots and it is really hot inside and seems not to cool at all in a reasonably amount of time. I went to Academy Sports and bought a high volume fan meant to blow up air mattresses and such. It uses 6 "C" cell batteries. Added a couple of feet of clear vinyl tubing that fits tight in the chamber. It really blows hard and will cool the barrel from the inside in about 2 minutes. Seems to work really well and using ambient air temperature to cool. Question is, is there any danger to the barrel cooling it this quickly? One thing is for sure, it is cheap and seems to work really well.

Kind a like this one ha ha no I don't feel there's any danger and cooling your barrel it's not going to cool it down so rapid that it would cause problems I drilled out a case to go in the chamber