Barrel temperature ?

#51
308pirate said:
Um....no

Heat checking/cracking is a real thing, and not just in rifle throats. The same exact failure mode is present in high pressure die cast tooling particularly when being injected with metals that have a higher melting point like copper and its alloys.

Heat, not pressure, kills barrels. Unless your put so much more pressure in it that you exceed the elastic deformation limit. Then yes, pressure kills barrels.
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You're missing the context, of course heat kills barrels. This thread is about just how hot a should you let the exterior of the barrel get before you stop? This seems to range from next to no heat at all (one group, then rest) to too hot to touch, which imo is virtually no heat at all.

If someone tells you their hand loaded 6cm died in 1k rounds, do you immediately think their rate of fire was too high, or that they're just loading way over max? Certainly they both play a roll, but one is obviously worse in this shooting discipline.
 
#52
I feel bad for guys that go through all the “barrel voodoo” I am in this to shoot waiting for a barrel to cool doesn’t sound like fun.

If you’re the type of guy waiting for your barrel to cool then you are probably the type that should know how to change a barrel. Quit being a fucking cheapskate shoot and enjoy life!
 
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#53
Supersubes said:
If someone tells you their hand loaded 6cm died in 1k rounds, do you immediately think their rate of fire was too high, or that they're just loading way over max?
Click to expand...

I get the context. To answer your question, I wouldn't wonder at all because it's not my rifle.

And no one can draw any correlations (at least not with any level of certainty) between barrel life and how far someone has pushed a load over max.
 
#56
Steel+Killer said:
I feel bad for guys that go through all the “barrel voodoo” I am in this to shoot waiting for a barrel to cool doesn’t sound like fun.

If you’re the type of guy waiting for your barrel to cool then you are probably the type that should know how to change a barrel. Quit being a fucking cheapskate shoot and enjoy life!
Click to expand...
Exactly…
 
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#57
Supersubes said:
If someone tells you their hand loaded 6cm died in 1k rounds, do you immediately think their rate of fire was too high, or that they're just loading way over max? Certainly they both play a roll, but one is obviously worse in this shooting discipline.
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1k isn't far off what I'd expect so it wouldn't surprise me at all but I'd tend to lean toward pressure before heat just because that's like 30% off of normal barrel life and that's really easy to do with continuous use of over-hot loads. You have to get a barrel pretty darn hot pretty darn often to make that kind of reduction from rate of fire alone.
 
#58
spamassassin said:
1k isn't far off what I'd expect so it wouldn't surprise me at all but I'd tend to lean toward pressure before heat just because that's like 30% off of normal barrel life and that's really easy to do with continuous use of over-hot loads. You have to get a barrel pretty darn hot pretty darn often to make that kind of reduction from rate of fire alone.
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I have a pet project 6cm I built a few years ago to see for myself what barrel life could be. Ive long thought that last 100 fps is doing a lot of damage. I chambered a 27” bartlein with a saami bodied reamer, and throated it out slightly past saami freebore (.190 vs .183). The plan was to shoot 115 dtacs at 2900 fps, or about 100-150 fps slower than is typical here on the hide. It’s never seen a velocity over 2920, and I’ve continually had to back down the charge to keep it at/under 2900 as the barrel sped up, and velocity didn't stabilized till ~700 rounds. I’m closing in on 800 rounds now and the throat erosion based off seating depth tests is less than .010. Many here report that much erosion per 100 rds. I think it will go 2500 rounds or more. By no means scientific, but by no means is it doing what many say it should.
 
#59
Didn't MDT do a test where they fired 500 or 1000 rounds straight, then sent the barrel back to the manufacturer. They cleaned it and shot it and it still shot 1 moa if I recall. So I wouldn't worry about shooting a Warm barrel
 
#60
Supersubes said:
I have a pet project 6cm I built a few years ago to see for myself what barrel life could be. Ive long thought that last 100 fps is doing a lot of damage. I chambered a 27” bartlein with a saami bodied reamer, and throated it out slightly past saami freebore (.190 vs .183). The plan was to shoot 115 dtacs at 2900 fps, or about 100-150 fps slower than is typical here on the hide. It’s never seen a velocity over 2920, and I’ve continually had to back down the charge to keep it at/under 2900 as the barrel sped up, and velocity didn't stabilized till ~700 rounds. I’m closing in on 800 rounds now and the throat erosion based off seating depth tests is less than .010. Many here report that much erosion per 100 rds. I think it will go 2500 rounds or more. By no means scientific, but by no means is it doing what many say it should.
Click to expand...
When I built my .243AI I wanted as much gumption as I could get into a .308win length AICS mag, I wanted 6mm to run DTACs just at 3200fps and I wanted >1500rds of barrel life so it would be able to make it through a whole year of matches. I knew it was going to be rough on tubes so I selected a polygonally rifled barrel that swaged the bullet instead of engraving it with a bore so slick it looked like glass. I chose the .243AI because it had enough powder capacity to hit my speed requirement and the shoulder angle put the flame intersection point inside the neck. When it was time to buy the bullets I got the HBN coated dtacs and never fed it anything but those. I ran 39gr of powder for fireforming and 45.5gr for full tilt match loads. I tried a number of powders but went with RL-23 because it seemed to generate pretty low peak pressures based on things like primer flattening and quick-load sims and such while delivering the 3200fps that I wanted. I ended up getting 1800rds before the throat got long enough that I couldn't maintain a .040 or less jump. My barrel life calculator spreadsheet suggested 1300rds would be about it. I shot at typical PRS match shot cadence in matches so I wasn't sparing the rod on rate of fire. I spared as much pressure as I could and selected every bit of the system for maximum barrel life. It worked. From this I deduce that pressure is mighty powerful in throat erosion but barrel temperature is relatively limp dicked in that respect. Not completely impotent but pretty flaccid.
 
#63
308pirate said:
Um....no

Heat checking/cracking is a real thing, and not just in rifle throats. The same exact failure mode is present in high pressure die cast tooling particularly when being injected with metals that have a higher melting point like copper and its alloys.

Heat, not pressure, kills barrels. Unless your put so much more pressure in it that you exceed the elastic deformation limit. Then yes, pressure kills barrels.
Click to expand...

So far as firing a cartridge goes, heat and pressure are fairly analogous. You will very rarely/never get more of one without more of the other. But yeah pressure alone won't do much for erosion.

Heat is obviously a factor in barrel wear and rate of barrel wear as a function of round count. The most obvious anecdotal example I have is the time I took a PSA AR-15 upper with my Thunderbeast CB brake on it and dumped 300 rounds on a F/A lower. Barrel/brake were glowing, gas tube got wrecked, etc. etc... In the aftermath, you could see obvious erosion in the CB brake and the bore (lost 150-200fps muzzle velocity from before to after). 300 rounds of slow fire in 5.56 means fuckall for wear/erosion.

So somewhere in between 1 round a minute and 300 rounds in 2 minutes there's an elbow in the curve... Where that is, I don't know. However, I tend to not worry about it in a bolt action. Like I said before, once you start getting heat off the barrel you can't see through it's probably time to give it a break.
 
#64
Ledzep said:
So far as firing a cartridge goes, heat and pressure are fairly analogous.
Click to expand...

I take it that you have some real subject matter expertise in the behavior of smokeless powder?

What is the relationship between flame temperature and chamber pressure with smokeless powder?

I'm asking for real evidence, like a chemical reaction formula showing the relationship, a technical paper, or something similar. Not "it's obvious think about it".

In my limited knowledge of physics and chemistry, the gas pressure generated by a burning solid is not directly related to the flame temperature of that burning substance.

In my opinion this is another one of the many gun world myths that get repeated so often they become truth. But I could very well be wrong.
 
#65
308pirate said:
I take it that you have some real subject matter expertise in the behavior of smokeless powder?

What is the relationship between flame temperature and chamber pressure with smokeless powder?

I'm asking for real evidence, like a chemical reaction formula showing the relationship, a technical paper, or something similar. Not "it's obvious think about it".

In my limited knowledge of physics and chemistry, the gas pressure generated by a burning solid is not directly related to the flame temperature of that burning substance.

In my opinion this is another one of the many gun world myths that get repeated so often they become truth. But I could very well be wrong.
Click to expand...
Ever hear of Boyle's law? Pressure and heat are directly related.
 
#66
308pirate said:
I take it that you have some real subject matter expertise in the behavior of smokeless powder?

What is the relationship between flame temperature and chamber pressure with smokeless powder?

I'm asking for real evidence, like a chemical reaction formula showing the relationship, a technical paper, or something similar. Not "it's obvious think about it".

In my limited knowledge of physics and chemistry, the gas pressure generated by a burning solid is not directly related to the flame temperature of that burning substance.

In my opinion this is another one of the many gun world myths that get repeated so often they become truth. But I could very well be wrong.
Click to expand...
Sustained critical temperatures kills barrels. It doesn’t matter how much you kick and scream otherwise. The critical temp is reached and kept there with rapid fire without cooling. The military recognized it years ago and tried to remedy it with chrome lined barrels.
Barrel makers recommend short shot strings to minimize it. Lots of data out there.
 
#67
spamassassin said:
Ever hear of Boyle's law? Pressure and heat are directly related.
Click to expand...

I'm extremely familiar with Boyle's Law. It's irrelevant in this case. For Boyle's law to apply, a rifle chamber would have to be a closed system in which an existing volume of gas is compressed. That's not what's going on in the chamber of a rifle, unless a rifle also has a compression cycle like a piston engine.

Thermodynamically and mechanically a rifle is the last two strokes of an otto cycle engine.
 
#68
Gohring65 said:
Sustained critical temperatures kills barrels. It doesn’t matter how much you kick and scream otherwise. The critical temp is reached and kept there with rapid fire without cooling. The military recognized it years ago and tried to remedy it with chrome lined barrels.
Barrel makers recommend short shot strings to minimize it. Lots of data out there.
Click to expand...

LOLDAFUQ
 
#70
308pirate said:
I'm extremely familiar with Boyle's Law. It's irrelevant in this case. For Boyle's law to apply, a rifle chamber would have to be a closed system in which an existing volume of gas is compressed. That's not what's going on in the chamber of a rifle, unless a rifle also has a compression cycle like a piston engine.

Thermodynamically and mechanically a rifle is the last two strokes of an otto cycle engine.
Click to expand...
Then no, you either don't understand Boyle's law or the definition of a closed system.
 
#72
Jmkjr87 said:
Didn't MDT do a test where they fired 500 or 1000 rounds straight, then sent the barrel back to the manufacturer. They cleaned it and shot it and it still shot 1 moa if I recall. So I wouldn't worry about shooting a Warm barrel
Click to expand...
Not sure if the test is true or not but if the result is 1moa…that barrel got tossed a long time ago.

1 Moa is 1995 accuracy

Modern factory rifles with crappy factory barrels shooting factory ammo can beat that out if the box.
 
#73
spamassassin said:
Then no, you either don't understand Boyle's law or the definition of a closed system.
Click to expand...

LOL.........Boyle's Law doesn't even have temperature in its formula and assumes a constant volume of gas.

There isn't a constant volume of gas in a rifle. The quantity of gas increases as a function of time, because...........wait for it............the mass of powder is burned into gas.

You have to do more than read wikidpedia
 
Last edited:
#76
308pirate said:
Let's ignore that hot ass flame burning at over 2000 F in your heat balance, shall we?
Click to expand...
Jesus, take a class already. Just because the system is internally subject to dynamic processes doesn't make it an open system. The container is still closed genius.

ETA: Perhaps a formal definition is called for because some people suffer Dunning-Kruger like a bitch:

A closed system is a type of thermodynamic system where mass is conserved within the boundaries of the system, but energy is allowed to freely enter or exit the system. In chemistry, a closed system is one in which neither reactants nor products can enter or escape, yet which allows energy transfer (heat and light).

Heat may enter or exit the system through transfer to other mediums like the bolt and the barrel. Nothing else leaves or enters until the bullet exits the pipe.
 
#79
brianf said:
Not sure if the test is true or not but if the result is 1moa…that barrel got tossed a long time ago.

1 Moa is 1995 accuracy

Modern factory rifles with crappy factory barrels shooting factory ammo can beat that out if the box.
Click to expand...
Your missing the point. They fired 1000 rounds straight, got the barrel wicked hot, enough to cook bacon on it and then it still shot around 1 moa. So to go and shoot 20 30 rounds and wait 5 mins and then do it again isn't much of a concern. Also 1 MOA gun will win PRS matchs in the right hands
 
#80
Jmkjr87 said:
Your missing the point. They fired 1000 rounds straight, got the barrel wicked hot, enough to cook bacon on it and then it still shot around 1 moa. So to go and shoot 20 30 rounds and wait 5 mins and then do it again isn't much of a concern. Also 1 MOA gun will win PRS matchs in the right hands
Click to expand...
1 moa custom barrel is trash.
Heat killed a barrel in 1000 rounds that otherwise should last 2500-3000 rounds.
If you shoot a overbore cartridge in 20-30 round strings you’ll trash it just as fast. It’s been proven on prairie dog fields for years.
 
#81
50 fast rounds and it went from 54 to 90 degrees?

Last time out mine went from about the same starting temp to... I don't recall. over 100 degrees anyway, in maybe 25 rounds(?) fired pretty dang slowly. Below max loads.

Shows there's lots and lots and lots of variables.
 
#82
spamassassin said:
Jesus, take a class already. Just because the system is internally subject to dynamic processes doesn't make it an open system. The container is still closed genius.

ETA: Perhaps a formal definition is called for because some people suffer Dunning-Kruger like a bitch:

A closed system is a type of thermodynamic system where mass is conserved within the boundaries of the system, but energy is allowed to freely enter or exit the system. In chemistry, a closed system is one in which neither reactants nor products can enter or escape, yet which allows energy transfer (heat and light).

Heat may enter or exit the system through transfer to other mediums like the bolt and the barrel. Nothing else leaves or enters until the bullet exits the pipe.
Click to expand...

I have never said the system is open.

What I have said, repeatedly, is that the volume isn't constant. What I have said, is that it is not a closed system IN WHICH THE GAS IS BEING COMPRESSED.

Not only is the system volume not constant, it's INCREASING. Remember that bullet going down the bore? So please hold a class on compressive heating of gas when the system volume is increasing.

Boyle's Law doesn't add any heating to the chamber/throat.

The throat dies due to flame cutting period. Chamber pressure has fuck all to do with this.

Again, you need to do more than recite wikidpedia
 
#83
308pirate said:
I have never said the system is open.

What I have said, repeatedly, is that the volume isn't constant. What I have said, repeatedly, is that nothing is compressing the gas in the system.

Not only is the system volume not constant, it's INCREASING. Remember that bullet going down the bore? So please hold a class on compressive heating of gas when the system volume is increasing.

Boyle's Law doesn't add any heating to the chamber/throat.

The throat dies due to flame cutting period. Chamber pressure has fuck all to do with this.

Again, you need to do more than recite wikidpedia
Click to expand...
Go away buttpirate. Heat kills barrels, you can puke shit all you want. Doesn’t change the facts.
 
#84
Jmkjr87 said:
Your missing the point. They fired 1000 rounds straight, got the barrel wicked hot, enough to cook bacon on it and then it still shot around 1 moa. So to go and shoot 20 30 rounds and wait 5 mins and then do it again isn't much of a concern. Also 1 MOA gun will win PRS matchs in the right hands
Click to expand...
I didnt watch the video yet but I will soon, but there are other reasons to shoot than PRS.

…1 Moa for “my personal wants” is not good enough.

Ask anyone on this entire site if the strive for 1 moa in general…even toss in some AR guys. You will get a resounding no.
 
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#85
Gohring65 said:
1 moa custom barrel is trash.
Heat killed a barrel in 1000 rounds that otherwise should last 2500-3000 rounds.
If you shoot a overbore cartridge in 20-30 round strings you’ll trash it just as fast. It’s been proven on prairie dog fields for years.
Click to expand...
Still missing the point
 
#89
308pirate said:
Boyle's Law doesn't add any heating to the chamber/throat.
Click to expand...
tell us you don't understand Boyle's Law without telling us you don't understand Boyle's Law.

Temperature increases with pressure. The relationship is well known. If this weren't the case then turbochargers wouldn't benefit from intercoolers. Before you spout off, know things.
 
#90
spamassassin said:
tell us you don't understand Boyle's Law without telling us you don't understand Boyle's Law.

Temperature increases with pressure. The relationship is well known. If this weren't the case then turbochargers wouldn't benefit from intercoolers. Before you spout off, know things.
Click to expand...

Temperature increases with pressure when a gas is compressed by a volume reduction.

When is volume reduced in that closed system between muzzle and breech?

There's a fire going on inside that same system. I think that's where all the heating comes from. But what do I know?
 
#93
Unless your running a over bore cartridge I wouldn't worry about firing 10 shots and then temping your gun untill it's cold. What faggotry
 
#95
6.5x47 lapua, im running 139 scenar @2732.
6.5 creed ain't bad
308 win
6BR
6XC
At a match you can't call a time out if your barrel is hot, barrels are a consumable
 
#96
Jmkjr87 said:
6.5x47 lapua, im running 139 scenar @2732.
6.5 creed ain't bad
308 win
6BR
6XC
At a match you can't call a time out if your barrel is hot, barrels are a consumable
Click to expand...
308 is the only one that wouldn’t be consider either close to overbore or is overbore. We know barrels are consumable, that’s not the question, the question is does heat kill barrels. If you’re running in a match you have to run hot. That’s the nature of the beast. You’re not aimlessly ruining a barrel. That’s running a requirement.
 
#97
Gohring65 said:
308 is the only one that wouldn’t be consider either close to overbore or is overbore. We know barrels are consumable, that’s not the question, the question is does heat kill barrels. If you’re running in a match you have to run hot. That’s the nature of the beast. You’re not aimlessly ruining a barrel. That’s running a requirement.
Click to expand...
Nobody is denying heat kills barrels. The question is how much and for how long. You make it sound like you can only fire 5 rounds and then have to pack up for the day. If I can get 1800 to 2500 rounds out of a barrel, the way I run em than that's fine by me. And I run em hard. My last barrel went 2400 rounds when I pulled it, the one before that went 2200 when I pulled it, im not gonna dick around when practicing. I want to shoot then go home
 
#98
Jmkjr87 said:
Nobody is denying heat kills barrels. The question is how much and for how long. You make it sound like you can only fire 5 rounds and then have to pack up for the day. If I can get 1800 to 2500 rounds out of a barrel, the way I run em than that's fine by me. And I run em hard. My last barrel went 2400 rounds when I pulled it, the one before that went 2200 when I pulled it, im not gonna dick around when practicing. I want to shoot then go home
Click to expand...
I don’t pack up for the day after 5 rounds. I pick up another rifle.
 
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