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Does anyone know of any studies relating to the affect carbon fouling has upon barrel heat dissipation and subsequent barrel life?

From what I’ve been able to discover is that the throat area and lands suffer the most from heat cracking due to the heat and pressure of fired rounds. As I understand it, M14 barrels are drilled to 0.3000” + 0.0004” and then the grooves are cut to 0.308”. Then the chamber reamer will taper the lands immediately following the throat down to 0.3000” to ease the bullet transition from the throat to the rifling.

What I don’t understand is if the carbon fouling, always heaviest in the throat and first few inches of the rifling, help or hurt heat dissipation. Does the carbon buildup on the lands act as a lubricant as the lands compress the bullet or does it act as an insulator preventing the rapid dissipation of heat? Would the carbon fouling in the grooves, less compacted than on the lands due to less pressure, act as an insulator inhibiting radiant heat loss from the lands?

Finally, while muzzle and throat wear has the greatest long term impact on accuracy, the cold/clean/fouled/hot barrel accuracy has the largest short term impact. Clean barrels, it seems, are prone to a shift in POI. I assume that if the barrel were to be cleaned following every shot, that the barrel’s accuracy might be very good but since most of us clean the barrel only after a trip to the range and a few of us clean after a string of shots, we adjust our sights to move the point of impact to our point of aim. Most of us will also pace our shots to keep the barrel at a reasonable temperature.

Shooting demonstrates that fouling has an initial positive impact upon accuracy but within 50 rounds or so, out groups will loosen up and, unlike the effects of a hot barrel, will not return to a consistent POI until the barrel has been cleaned.

I would imagine that the effect of carbon fouling would be so slow that its results wouldn’t be noticeable; those who clean infrequently might have to occasionally adjust their POA to compensate for the fouling, but barrel heat and cool down times wouldn’t even come to mind. The only effect that would be noticeable, if enough rounds are fired, would be barrel life.

Does a frequently cleaned barrel last longer than a typically fouled barrel?
 

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Does anyone know of any studies relating to the affect carbon fouling has upon barrel heat dissipation and subsequent barrel life?

From what I’ve been able to discover is that the throat area and lands suffer the most from heat cracking due to the heat and pressure of fired rounds. As I understand it, M14 barrels are drilled to 0.3000” + 0.0004” and then the grooves are cut to 0.308”. Then the chamber reamer will taper the lands immediately following the throat down to 0.3000” to ease the bullet transition from the throat to the rifling.

What I don’t understand is if the carbon fouling, always heaviest in the throat and first few inches of the rifling, help or hurt heat dissipation. Does the carbon buildup on the lands act as a lubricant as the lands compress the bullet or does it act as an insulator preventing the rapid dissipation of heat? Would the carbon fouling in the grooves, less compacted than on the lands due to less pressure, act as an insulator inhibiting radiant heat loss from the lands?

Finally, while muzzle and throat wear has the greatest long term impact on accuracy, the cold/clean/fouled/hot barrel accuracy has the largest short term impact. Clean barrels, it seems, are prone to a shift in POI. I assume that if the barrel were to be cleaned following every shot, that the barrel’s accuracy might be very good but since most of us clean the barrel only after a trip to the range and a few of us clean after a string of shots, we adjust our sights to move the point of impact to our point of aim. Most of us will also pace our shots to keep the barrel at a reasonable temperature.

Shooting demonstrates that fouling has an initial positive impact upon accuracy but within 50 rounds or so, out groups will loosen up and, unlike the effects of a hot barrel, will not return to a consistent POI until the barrel has been cleaned.

I would imagine that the effect of carbon fouling would be so slow that its results wouldn’t be noticeable; those who clean infrequently might have to occasionally adjust their POA to compensate for the fouling, but barrel heat and cool down times wouldn’t even come to mind. The only effect that would be noticeable, if enough rounds are fired, would be barrel life.

Does a frequently cleaned barrel last longer than a typically fouled barrel?
The Lands are what drives the bullet and as such there isn't real carbon built up on them but there is some discoloration, The Grooves are what collect/trap most of the carbon build up. Cleaning a barrel of all copper may not be the best for barrels the copper will fill in small imperfection and allow the bullet too pass over the blemish without pulling on the bullets jacket. If you were too remove every last spec of copper your going too have too season the barrel again, repave the road so too say. So some copper is good, too much isn't.

I don't think that there is any luberous effects of carbon, if there was we would never clean the barrel. Carbon attracts moisture not good for rifle bores, and thats why we sweep/swab it out.

The only person I know of that did any heat test on the M1A barrel was .30Caliber and it was I think was a FYI and not very scientific. He used heat strips near the chamber and near the G/C. Surprisingly the chamber end saw the smallest temp change the the G/C the greatest, its been sometime ago and I'm going from memory.

Does a clean barrel last longer than a dirty barrel, I don't think so 90% of barrel wear comes from improper cleaning like dragging the cleaning rod along the muzzle or from chemicals that are too harsh and can etch the bore.

my .02
 
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Scrubbing the crap out of barrels does more to shorten their life than anything else.
Especially when abrasives such as Isso, JB and KG12 are used.
Not necessarily, it depends on what tools and chemicals you use and how you use them.
 

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Does a frequently cleaned barrel last longer than a typically fouled barrel?
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I doubt that cleaning would make a difference on barrel life, unless the chemicals or cleaning procedure itself caused damage.

But not cleaning can cause functional problems if there is so much fouling in the shoulder area of the chamber that it gives headspace problems.

I suspect that many of the stories about cleaning rod damage are related to military training situations where a DI insists that the barrel is squeeky clean, and the grunts don't GaS about using the rod properly.

I suspect that most recreational shooters who buy their own equipment treat the barrel and rod more carefully.

Jay Kosta
Endwell NY USA
 

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Shooting demonstrates that fouling has an initial positive impact upon accuracy but within 50 rounds or so, out groups will loosen up and, unlike the effects of a hot barrel, will not return to a consistent POI until the barrel has been cleaned.
No it doesn't. I haven't cleaned mine in probably 200 rounds and it is still grouping the requisite 1.5MOA with consistent point of aim/impact.
 

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Discussion Starter · #8 ·
Phil: “I don't think that there is any lubricous effects of carbon, if there was we would never clean the barrel.”

Without knowing the composition of the carbon fouling, it could either be an abrasive, a lubricant or neither. Graphite is often used in car door locks as a non-freezing lubricant during the winter here in Minnesota. It would be interesting to know exactly what the composition of fouling is, but I’m sure that it varies from powder to powder.

As to the lands being relatively carbon free, that makes sense to a point, but then we’d have to figure out where the fouling went. Is it possible it all gets swept into the grooves? Some might, especially the fouling near the edge of the lands, but I suspect most would be forced out the muzzle and the rest would be pressed and heated into a very hard residue on the land itself.

Jay: “I suspect that many of the stories about cleaning rod damage are related to military training situations where a DI insists that the barrel is squeeky clean, and the grunts don't GaS about using the rod properly.”

In boot camp, we used the standard GI cleaning rod and you’re right, we slammed those barrels trying to figure out shortcuts to bright, shiny bores. Our longest distance was 500 meters (Camp Stuart Mesa, later renamed to Camp Geiger) and there we had a 36” bulls eye if I recall correctly, and we would get maximum score just for being in the black. So a 7MOA rifle would be good enough to qualify as an expert. Still, those rifles went from platoon to platoon throughout the year and probably year after year. There was only one rifle in my platoon that was replaced due to accuracy problems.

Rammac: “Not necessarily, it depends on what tools and chemicals you use and how you use them.”

Ammonia, I have read, will etch certain types of steel if left on too long. While carbon is generally not dissolvable, there are some forms of organic carbon that can be dissolved. Top end engine cleaner (TEC) requires heat and time to work properly. Like using Kroil, the TEC penetrates the metal of the intake manifold and breaks the carbon/metal bond, sweeping the carbon out with the exhaust gases.

It is mostly the mechanical action of bore brushes and patches combined with the loosening of the carbon/metal bond by the solvent’s penetration between the carbon and metal that cleans the bore. Cleaning a heated barrel is much easier than a cold one I suspect, because the heat, like using TEC on an engine, assists the solvent penetration between the carbon and metal.
 

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Phil: “I don't think that there is any lubricous effects of carbon, if there was we would never clean the barrel.”

Without knowing the composition of the carbon fouling, it could either be an abrasive, a lubricant or neither. Graphite is often used in car door locks as a non-freezing lubricant during the winter here in Minnesota. It would be interesting to know exactly what the composition of fouling is, but I’m sure that it varies from powder to powder..
It would be neat too know but what good would that info be? I think it would take a rather large amount on burt powder too have any testable quantity of what was left over. In truth I don't think anyone really cares about what is left over and until someone does we won't know.

Yes, Graphite is a lube, but the sole reason its added too powders is too control there burning speed not lube the tube for the next bullet fired. I think its best too just call burnt powder residue what it is, carbon fouling or soot. Reguardless its a moisture magnet if left in the bore, patch/swab it out and be done with it.............
 
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