Carbon barrels

[ejg]

I have been hunting with a carbon barrelled rifle since half a year and had some nice tumbles. Barrel is like new. The really nice thing about carbon rifle in the winter is that if you pick up the rifle on on the barrel or use the rifle as a stick in the hills it is not cold like steel.... so much for the great thermal transfer that I don't quite believe.
We have had maybe ten carbon barrels of at least two brands come through our workshop, one issue is if one leaves masking tape on a bit too long it can pull very small carbon fibres off the barrel.
edi

 

[Frog4aday]

My gun smith who builds lots of guns told me that the average failure for carbon barrels is about 10%. <snipped stuff>

This (what @rockwallraider posted) is what we've been seeing both on failures and replacement.

I feel ignorant, but have to ask: What constitutes a "carbon barrel failure"? Delamination of the carbon fiber? A poor shooting barrel? Barrel 'blows up' when round is fired?

 

[elkaholic]

I feel ignorant, but have to ask: What constitutes a "carbon barrel failure"? Delamination of the carbon fiber? A poor shooting barrel? Barrel 'blows up' when round is fired?

Our experiences all started with high pressure and low velocity. The cases I've heard back from are inconsistencies in bore diameter (bulge) restricting the bullet travel and building pressure. To their credit, they have taken care of the problems as far as Im aware of. My guess is that this is caused by the carbon wrapping process over a thin steel cylinder, but Im not a barrel maker so that's just speculation?

 

[Frog4aday]

Thanks elkaholic! That's interesting. I never thought about that (wrapping the 'thin' steel barrel with CF causing distortions within the internal dimensions.)

 

[elkaholic]

Thanks elkaholic! That's interesting. I never thought about that (wrapping the 'thin' steel barrel with CF causing distortions within the internal dimensions.)

Thats my guess?
I will say this though. As someone who deals in this industry, there are always problems that arise with any of us. These guys are taking care of the issues so I would ask everyone to give them a chance to work them out!

 

[RockyRandy]

I don't think strength is a problem what i would be more concerned about is the heat build up issue. I have a friend that did a lot of testing for Christensen Arms and he proved that they don't cool down like a steel barrel does. He told me that they had changed how they wrap their barrels and it has helped. Don't think this is a big deal if all your going to do is hunt with the rifle but if your shooting long range matches in 80 plus temps then i would rethink it pretty hard. Just my opinion.

 

[Cdub338]

I don't think strength is a problem what i would be more concerned about is the heat build up issue. I have a friend that did a lot of testing for Christensen Arms and he proved that they don't cool down like a steel barrel does. He told me that they had changed how they wrap their barrels and it has helped. Don't think this is a big deal if all your going to do is hunt with the rifle but if your shooting long range matches in 80 plus temps then i would rethink it pretty hard. Just my opinion.

From first hand experience, I can tell you that after 30+ rounds in fairly rapid succession, the barrel stayed cool to the touch the whole time. I had to keep messing with my Magneto Speed bayonet. The muzzle break was smokin hot by comparison.

 

[Danny1788]

From first hand experience, I can tell you that after 30+ rounds in fairly rapid succession, the barrel stayed cool to the touch the whole time. I had to keep messing with my Magneto Speed bayonet. The muzzle break was smokin hot by comparison.

just because the outside CF is cool to the touch doesn't mean the inside steel of the barrel wasn't smoking hot as well. They have different heat dissipation rates.

 

[Zymurgist]

just because the outside CF is cool to the touch doesn't mean the inside steel of the barrel wasn't smoking hot as well. They have different heat dissipation rates.

A material's ability to conduct heat can be measured, steel is around 50 watts per sq. meter-kelvin. The thermal coefficient going across the weave and resin of a CF barrel is about 5W/mk for a metal powder doped resin. The CF wrapped around a steel bore core acts more as an insulator as it is thermally inefficient compared to an all steel barrel.

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 even while a CF barrel may not feel feel hot to the touch.

The steel bore core and CF composite have different coefficients of expansion and as they heat up will cause mechanical stresses in the barrel moving your zero and degrading your shot repeatability. Many CF rifle owners buy/build devices to blow air through the bore of their rifle to cool them between shots. Keep in mind CF barrels require a bit more effort in their care and feeding.

 

[Danny1788]

A material's ability to conduct heat can be measured, steel is around 50 watts per sq. meter-kelvin. The thermal coefficient going across the weave and resin of a CF barrel is about 5W/mk for a metal powder doped resin. The CF wrapped around a steel bore core acts more as an insulator as it is thermally inefficient compared to an all steel barrel.

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 even while a CF barrel may not feel feel hot to the touch.

The steel bore core and CF composite have different coefficients of expansion and as they heat up will cause mechanical stresses in the barrel moving your zero and degrading your shot repeatability. Many CF rifle owners buy/build devices to blow air through the bore of their rifle to cool them between shots. Keep in mind CF barrels require a bit more effort in their care and feeding.

This is what I was trying to say in less words, And your explanation is spot on and a lot more informative than my response.

 

[Tech4]

This may not have anything to do with this but I hunt with CF arrows and they shatter when they hit something hard and I get new arrows that are not straight.