My experience: BSF Barrels May Experience Substantial Thermal Drift.

[grayfox]

Here is a short article describing why they are trying to use carbon fiber for greater thermal conductivity (cooling).
When I saw the cooling slots on the BSF barrel I thought, WTF. It shouldn't need them.
Stiffness is another benefit.
https://christinedemerchant.com/carbon_c...ivity.html
Here is another manufacturer that uses continuous carbon fiber and states the benefit of increased cooling rate.
https://www.proofresearch.com/the-products/barrels/

Wish I still had my materials science PhD guys around... had to leave them back at the agency when I retired...
I read thru the first one briefly and seems like CF could have good conductivity. Note however that it would not be the "Graphite" number (300-1500) but the (lower) CF one of 21-180. Maybe better than steel I would say but not orders of magnitude. I wonder if the tested setup is conductivity along the fiber or across a wrap of several fibers in a cylindrical volume, like would be as the exterior of a barrel... hmmm. Also what temp difference does it take to conduct across from the steel to fiber, across that boundary between the two...

I do wonder at the statement that conduction in metal comes via free electron motion (electrons don't have a lot of mass and so cannot convey a lot of thermal energy)... free electron contributions are more akin to electrical current, my understanding of heat flow is that it is via vibration of the atoms/molecules in the metal lattices, energy flowing from higher temperatures (higher vibes) to lower ones. That being said CF still might have a higher conductivity coefficient, its range (21-180) is both higher and lower than carbon steels (~68-80).

I also wonder at the actual, physical construction of the CF wrap... is it a series of fibers wrapped "tightly" or is it a weave of materials, or what... for steels, we know it is a continuous latticework of metallic material, no physical gaps (or very tiny micro-gaps, fractions of microns)... ie, a non-continuous material will have physical barriers for the heat to cross, one fiber at a time, whereas that is not so across the metal volume. This could make a difference and effectively slow the heat flow through a CF weave. I wonder if anyone has published actual test values of conductivity across the CF barrel, radially out, across the wrap as would be when it has to function in use...? Have we seen any test results on that? that would tell us a lot, but it could also vary from mfr to mfr since each one would have its own design specs.