Lead and copper fouling in barrel

[buckshotshoey]

Is the major source of lead/copper fouling in a barrel due to friction? Or is it due to the hot powder gasses vaporizing the metal and depositing down the barrel?

My opinion is vaporization. Hodgdon CFE powder works (I think) by chemically not allowing the vaporized copper to stick to the barrel.

Discussion?........

[jski]

I have read with lead, it's from vaporizing.

That's why I much prefer GC bullets. Linotype also helps because the alloy vaporizes at a higher temp ... again, from what I've read.

[Dusty Bannister]

I have read with lead, it's from vaporizing.

That's why I much prefer GC bullets. Linotype also helps because the alloy vaporizes at a higher temp ... again, from what I've read.

This would seem to be counter intuitive. Lead melts at 621 F and lino melts at 465 F ? As to temperature turning anything to vapor, it does not seem to have that affect on paper patching so why would it affect lead?

[Rcmaveric]

The amount of time of time a bullet is the barrel does not lend itself enough time to be damaged by heat due heat to transfer properties. Numerous articles tend to point that cast bullet leading happens from undersized bullets and/or when the bullet jumps the throat. That momentary gas cutting around the bullet base when it jumps the throat from bullet case to rifling or at any time the bullet is traveling down the barrel. If a crack happens and hot gasses shoot up the side of the bullet, it arc welds the bullet. Temporally making a molten skin that smears. Barrel condition is also important, but that is for abrasion to the projectile. A rough barrel with sharp edges will lead due to filing the bullet. As the next bullet passes it irons it out and starts a chain reaction that makes it worse. Leading from abrasion is easy to clean out because its not soldered to the barrel. Leading from gas cutting will be harder to clean out because it is soldered in place. To be soldered the metal and lead have to be the same temperature. I have read a few other articles that say lead can blasted off the bullet when it jumps the throat and causes in accuracy when it gets run over by the passing bullet. I have a hard time believing in lead being vaporized due to its ultra low heat transfer properties. If the lead was really vaporized a lot more of us would have lead poisoning from inhaling and/or swallowing it.

From the articles that i have read about jacket bullets, they never say why it happens but it tends to start in areas with high abrasion characteristics (tops of lands, throats ext.) and gets progressively worse causing a rapid decline accuracy. The reason copper fouling is so bad is because of its corrosion properties. If not cleaned out it will eat away and pit your barrel.

[Rcmaveric]

Is the major source of lead/copper fouling in a barrel due to friction? Or is it due to the hot powder gasses vaporizing the metal and depositing down the barrel?

My opinion is vaporization. Hodgdon CFE powder works (I think) by chemically not allowing the vaporized copper to stick to the barrel.

Discussion?........

Or its abrasion, the CFE could leave behind a sooty coating that prevents things from adhering to the barrel or eases friction... (like smoking a mold or putting pam on a griddle before cooking pancakes). Because a properly cleaned and cared for barrel would most likely never notice copper fouling. Most statesment indicate that you would never notice the difference of the CFE powder unless you shot 100+ shot strings or were not in the practice of cleaning your guns often. If i clean my barrels and oil them and never have a problem with copper fouling..... makes me lean more to abrasion.

[lwknight]

Shooting ranges just do not make a consideration for people that have proper bullet fit and proper loads. They just assume that you are a leadder poisoning the air.

[buckshotshoey]

Heat and pressure are related to each other. It's not just the heat from the powder being burned, but 50000 psi( or more in a rifle), and the oxygen content of the powder adds up. It leads me to this question.... How can a material build 50000 psi+ in such a short time, without an extreme build up of heat?

It might not be the best comparison, but think of a cutting torch. You heat the metal and press the oxy lever. The flame is not getting hotter, but the added pure oxygen is oxidizing the hot metal to remove it.

I read once that for a split second, the powder burn and pressure combine to make a flame hot enough to be considered plasma. This is also why some barrels seem to burn out faster then others. Think .243 here. They have a reputation for relatively short (compared to the parent .308 cartridge) lives.

I'm not an expert, but the subject of internal ballistics intrigues me. Keep the different points of view coming.

[buckshotshoey]

Or its abrasion, the CFE could leave behind a sooty coating that prevents things from adhering to the barrel or eases friction... (like smoking a mold or putting pam on a griddle before cooking pancakes). Because a properly cleaned and cared for barrel would most likely never notice copper fouling. Most statesment indicate that you would never notice the difference of the CFE powder unless you shot 100+ shot strings or were not in the practice of cleaning your guns often. If i clean my barrels and oil them and never have a problem with copper fouling..... makes me lean more to abrasion.

Possible. Have you tried running Sweets copper remover through your barrel? You might be surprised what you get out.

I was trying to find where I read about barrel leading. The only reference to lead vaporizing I can find in my reloading manual is this.....

".... Black powder fouls small bores more quickly then larger ones; fortunately the development of nitrocellulose, or smokeless propellants, largely eliminated the fouling problem. However another problem appeared. Smokeless propellants produced higher temperatures then black powder and caused sever barrel leading as hot gases melted the base of lead bullets."

(Speer #13, page 39)

I'm still looking for more info.

[buckshotshoey]

The only other reference I can find is mentioning lead exposure in indoor ranges....

"Full metal jacket bullets have traditionally been manufactured forming a jacket and then inserting a lead core from the rear. This leaves exposed lead at the base along with a folded edge of jacket material. The exposed lead can be melted by the heat from the burning powder charge contributing to airborne lead in indoor ranges."

This was in the TMJ pistol bullets section.
Speer 13, page 427.

[lwknight]

I watched a guy light off tracer rounds with a propane torch on youtube. They did not light readily but took a good bit of heating. The bullets had what looked like a reversed gas check so that the pyro stuff was not in direct communication with the burning powder. Evidently there is some kind of pressure fuse.
Anyway, it is pretty much the consensus that fouling is caused by flame cutting in a skidded rifling or a poorly fit bullet and not from flames to the base of the bullet.
And I also agree that a rough barrel will foul quickly compared to a slick barrel. Maybe each bullet pushes the fouling from the last out of a slick barrel each time. I have slugged a barrel where the slug comes out looking akin to a porcupine on the forward end from lead shards in the grooves being pushed out.

[buckshotshoey]

I watched a guy light off tracer rounds with a propane torch on youtube. They did not light readily but took a good bit of heating. The bullets had what looked like a reversed gas check so that the pyro stuff was not in direct communication with the burning powder. Evidently there is some kind of pressure fuse.
Anyway, it is pretty much the consensus that fouling is caused by flame cutting in a skidded rifling or a poorly fit bullet and not from flames to the base of the bullet.

That's why I'm in a dilemma. The info in the reloading manual seems to differ.

[303Guy]

The boolit base is untouched by the heat. As has been mentioned, gas cutting does take place if there is any leak. But aside from that, frictional heat will melt or soften and smear lead when there is insufficient lube between boolit and bore.

Bore to jacket friction can heat the jacket to produce heat discoloration - and expand the jacket enough to stop the bullet in the bore, which then basically drops out once it has cooled. That's with very small powder charges of course.

[Rcmaveric]

Heat and pressure are related to each other. It's not just the heat from the powder being burned, but 50000 psi( or more in a rifle), and the oxygen content of the powder adds up. It leads me to this question.... How can a material build 50000 psi+ in such a short time, without an extreme build up of heat?

It might not be the best comparison, but think of a cutting torch. You heat the metal and press the oxy lever. The flame is not getting hotter, but the added pure oxygen is oxidizing the hot metal to remove it.

I read once that for a split second, the powder burn and pressure combine to make a flame hot enough to be considered plasma. This is also why some barrels seem to burn out faster then others. Think .243 here. They have a reputation for relatively short (compared to the parent .308 cartridge) lives.

I'm not an expert, but the subject of internal ballistics intrigues me. Keep the different points of view coming.

Barrels are burned out from the wear at the throat from copper jackets and max pressures. Compition shooters will set back their barrel to get a few hundred more shots off. Properly cared for a cast bullet barrel last generations. The pressures and heat generated from your line of thinking are fractions for cast bullets as they are for their jacketed cousin loads.

[Rcmaveric]

I watched a guy light off tracer rounds with a propane torch on youtube. They did not light readily but took a good bit of heating. The bullets had what looked like a reversed gas check so that the pyro stuff was not in direct communication with the burning powder. Evidently there is some kind of pressure fuse.
Anyway, it is pretty much the consensus that fouling is caused by flame cutting in a skidded rifling or a poorly fit bullet and not from flames to the base of the bullet.
And I also agree that a rough barrel will foul quickly compared to a slick barrel. Maybe each bullet pushes the fouling from the last out of a slick barrel each time. I have slugged a barrel where the slug comes out looking akin to a porcupine on the forward end from lead shards in the grooves being pushed out.

i will have to agree.. Diesel engines work off compression igniting the mixture, not spark. Not all tracers ignite imidiately, some have a delay.Most references say that its ignited by the powder charge.

Also, think shock wave. Hypothesis: There is air space behind the bullet between the powder charge. When the powder goes off the gasses expand pushing that air cushion behind the bullet. Also may explain the bases protection from heat damage. There is also the candle theory: run your hand past a candle flame, move your hand fast enough and it doesn't burn you.

[buckshotshoey]

All plausible theories. The reference to diesel engines is interesting. Diesel fuel ignites because the pressure created brings the fuel up past it's flash point (pressure creates heat, heat creates pressure... laws of thermaldynamics). But the difference is the fuel is injected AFTER the pressure is already built up.

I'm not too old to learn, and I'm not going to say anybody here is wrong....yet.... but someone needs to give me a reference to prove the Speer manual wrong.

The "passing your hand over the candle" theory is hard for me to digest. Fire 3 rounds in 30 seconds. Then measure the temperature difference of the barrel. It obvious even after 1 round. Try passing your hand over a cutting torch! Lol Noticeable difference.

The throat erosion statement seems correct. You probably won't get much erosion at cast boolit pressures. High pressure equates to high temperatures, and the high content of built in oxygen erodes the throat....ie....flame cutting. I don't believe it's from jacket friction, or all different caliber barrel throats that run at simular pressures would errode at a simular rate. And they dont.

Like I said, I'm trying to learn something. Can anyone give reference material to back up your claims?

[Wayne Smith]

The 'flame cutting' from high pressure rounds is actually mostly heat abrasion from super heated grains of powder - it has little or nothing to do with the bullet. Continue to do your research, but do it from recognized sources of internal ballistics.

[buckshotshoey]

The 'flame cutting' from high pressure rounds is actually mostly heat abrasion from super heated grains of powder - it has little or nothing to do with the bullet. Continue to do your research, but do it from recognized sources of internal ballistics.

So is it more a sandblasting effect? Or does the heat from that effect have more to do with it? The errosion problem seems to happen quicker to smaller bore diameters with large case capacities. Im thinking 220 swift compared to .223. here.

[RED BEAR]

This one is a bit over my head I just shoot em and clean em. After shooting em they are dirty not sure why thats just the way it works. Good luck trying to figure it out.

[JimB..]

Thinking about gas flow, a subject about which I know nothing, it seems plausible that the base of the bullet will absorb some heat and that it will then be protected by that slightly cooler pocket of gasses, whereas if the bullet doesn’t seal to the bore the hot gasses will pass the bullet and continuously heat it in that spot.

[303Guy]

Here is a recovered boolit showing gas cutting.



What doesn't show in this photo is the exposed base shows zero heat effects.

Remember that the 'gas' behind a boolit is not just hot air but rather, is full of 'dust' particles, which could be considered abrasive.

On throat erosion (sorry, no reference), it has been reported that some powder produce more throat erosion than others (stick powders I think).

Here is a different boolit. Here it is clear that there has been no boolit base heat effects. There is no gas erosion either.



This one has gas erosion and shows no effects on the exposed base. The raised centre area is expose while the dented ring is from the paper patch.