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Fluted Bartlein vs Proof Research sendero contours
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<blockquote data-quote="Pdvdh" data-source="post: 1400829" data-attributes="member: 4191"><p>I expect the bore life of a CF barrel and a steel barrel will be identical at slow rates of fire. The bores in both barrels are made with the exact same steel. The steel is what's exposed to the flame thrower in both barrels.</p><p></p><p>The CF barrel will cool a tad bit slower but that difference is inconsequential for slow rates of fire.</p><p></p><p>So if there's going to be any benefit from a better cooling rate, that benefit will only begin to be realized at higher rates of fire sustained long enough for one barrel bore to elevate in temperature notably over the other.</p><p></p><p>So this is the focus of my criticism. The CF barrel manufacturers claim superior cooling. That their barrels cool more efficiently than steel barrels, which implies cooler temps and less overheating of the bore. Sustained higher rates of fire is what notably shortens accurate bore life.</p><p></p><p>The only scenario in which one barrel will benefit from shedding heat at higher rates is sustained fire. Sustained fire elevates steel temperatures in both barrels. Steel is an effective heat sink. It soaks up and stores a fair quantity of heat energy. Sustained high steel temperature is a close approximation to steady state heat transfer. In steady state heat transfer analysis, the thermal conductivity coefficient is the standard method of analytical solution. The Christensen Arms engineer has provided the thermal conductivity coefficients for their CF wrap and it's 69.5 times worse than steel in the shortest direction of flow, radially outward. A 69.5 times lesser rate of heat transfer thru the CF wrap than steel, by Christensen Arms own thermal conductivity coefficients. That's all there is. End of story.</p><p></p><p>However the Christensen Arms engineer disregarded the inferior thermal conductivity of their CF wrap, and diverted attention to thermal diffusivity, as if it more properly represents the rate of heat transfer thru their CF barrel wrap. Thermal diffusivity is useful in heat transfer analysis under transient, temporary, quickly changing temperature boundaries, like firing one single cartridge in a barrel. But I think we all recognize that the single shot fired isn't a temperature generating concern, and that neither barrel will offer a measurable advantage under single shot use. Also, IF the CF barrels were 100% CF, even the bore, the thermal diffusivity could be a little more pertinent. But their barrels have steel liners. Presenting the thermal diffusivity of the CF wrap as evidence of the superior cooling property of CF barrels is misleading, and flawed science.</p><p>The Christensen Arms engineer may not understand the flaw in his contentions. Perhaps that's the company line used to support the claim of better heat shedding, cooler running barrels. Or he may understand and gambled on smart AND clever, to spin a tale which supports their advertising claims, and more barrel sales.</p><p></p><p>The CF barrels are stiff and lightweight and evidently shoot well. Why not leave it at that, rather than adding the false advertising. Because at sustained higher rates of fire, the only scenario where one barrel will materially benefit from more efficient heat transfer above the other, the steel barrel will transfer heat at higher rates, and cool more quickly than the insulated CF wrapped barrel.</p></blockquote><p></p>
[QUOTE="Pdvdh, post: 1400829, member: 4191"] I expect the bore life of a CF barrel and a steel barrel will be identical at slow rates of fire. The bores in both barrels are made with the exact same steel. The steel is what's exposed to the flame thrower in both barrels. The CF barrel will cool a tad bit slower but that difference is inconsequential for slow rates of fire. So if there's going to be any benefit from a better cooling rate, that benefit will only begin to be realized at higher rates of fire sustained long enough for one barrel bore to elevate in temperature notably over the other. So this is the focus of my criticism. The CF barrel manufacturers claim superior cooling. That their barrels cool more efficiently than steel barrels, which implies cooler temps and less overheating of the bore. Sustained higher rates of fire is what notably shortens accurate bore life. The only scenario in which one barrel will benefit from shedding heat at higher rates is sustained fire. Sustained fire elevates steel temperatures in both barrels. Steel is an effective heat sink. It soaks up and stores a fair quantity of heat energy. Sustained high steel temperature is a close approximation to steady state heat transfer. In steady state heat transfer analysis, the thermal conductivity coefficient is the standard method of analytical solution. The Christensen Arms engineer has provided the thermal conductivity coefficients for their CF wrap and it's 69.5 times worse than steel in the shortest direction of flow, radially outward. A 69.5 times lesser rate of heat transfer thru the CF wrap than steel, by Christensen Arms own thermal conductivity coefficients. That's all there is. End of story. However the Christensen Arms engineer disregarded the inferior thermal conductivity of their CF wrap, and diverted attention to thermal diffusivity, as if it more properly represents the rate of heat transfer thru their CF barrel wrap. Thermal diffusivity is useful in heat transfer analysis under transient, temporary, quickly changing temperature boundaries, like firing one single cartridge in a barrel. But I think we all recognize that the single shot fired isn't a temperature generating concern, and that neither barrel will offer a measurable advantage under single shot use. Also, IF the CF barrels were 100% CF, even the bore, the thermal diffusivity could be a little more pertinent. But their barrels have steel liners. Presenting the thermal diffusivity of the CF wrap as evidence of the superior cooling property of CF barrels is misleading, and flawed science. The Christensen Arms engineer may not understand the flaw in his contentions. Perhaps that's the company line used to support the claim of better heat shedding, cooler running barrels. Or he may understand and gambled on smart AND clever, to spin a tale which supports their advertising claims, and more barrel sales. The CF barrels are stiff and lightweight and evidently shoot well. Why not leave it at that, rather than adding the false advertising. Because at sustained higher rates of fire, the only scenario where one barrel will materially benefit from more efficient heat transfer above the other, the steel barrel will transfer heat at higher rates, and cool more quickly than the insulated CF wrapped barrel. [/QUOTE]
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