Fact or fiction? Shooting through a hot barrel decreases barrel lifespan

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orpington

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I don't shoot nearly enough to determine if this is an old wives tale. And, if so, what is the definition of hot? The temperature obtained by several rounds fired in short succession on a hot day, hot enough to be mildly uncomfortable to the touch, or anything greater than ambient temperature?
 
Assuming you get the barrel red hot, I imagine continuing to shoot would at the very least accelerate the decay of the rifling.

But after just a few magazines? Not buying that one.
 
I would say fact at some point you will have a material hot enough to melt. Before that it will erode abruptly.

Takes quite a bit to do it thought. Lots of tests have been done to the point of destructive, Google videos of destruction tests, should get a number of hits.
 
Barrels don't get hot enough to harm them until their temperature gets up to about 200 degrees C; 390 degrees F.

I've seen no difference in .308 Win barrel life wearing out with some shot no faster than about once a minute to others that had 40% of their rounds fired 10 times a minute.
 
In naval rifles (or ordinance with pre-engraved driving bands) the magic number is 4-5 rounds per minute. But, that charges running 60 to 180# that are getting close to being a plasma on ignition.

Which is why such weapons have removable liners--the rifling will wear out (progressive rifling not helping that erosion, either).

I know of some "precision shooters" who act as if any more than 1 round per minute in their bolt actions will ruin the rifling, and heaven forfend that they not completely clean the barrel between shots.
 
US Navy guns 6", 8" and 16" all had uniform rifling; none are progressive except for early 16"/45 guns on USS North Carolina and USS South Dakota. They had a twist of increasing RH 1:50 calibers to 1:32 calibers at the muzzle. 16" barrel twist was 1:25 caliber or 1:400 inches so the projectiles leaving at 2500 fps spun 4500 rpm.

16" full charge was six 110-pound bags of powder. 300 to 350 round barrel life. 2 rounds per minute.

8" gun full charge was 85 pounds of powder. 3 to 4 rounds per minute. 700 round barrel life.

6" gun full charge was 33 pounds. 8 to 10 rounds per minute. 750 to 1000 round barrel life.

All projectiles' rotating bands were not pre-engraved. They got rammed into the rifling when loaded.

Their liners were used so regunning was simple; lots easier to pop the liner out the back of the turret then slide another one in. Liners grew several thousandths inch for every shot and their muzzle had to be turned back every so often when it grew half an inch or so past the muzzle else it would soon crack and break off causing accuracy problems. Liners were only a couple inches thick; much less weight than the complete barrel and cheaper, too.

NRA match rifle competitors shooting rapid fire matches shoot two 10-shot strings in rapid fire matches 60 to 70 seconds each. Sierra and Hornady shoot ammo that fast testing bullets for accuracy. Their barrels last as long as match rifle barrels fired once a minute; 3000 rounds or so for the .308 Win cartridge.
 
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There are several studies that discuss the fact that the interior surface of barrels reach temperatures of 1000 to 2000 degrees F but only for a few milliseconds. Due to the thickness of the barrel and the normal rate of fire, the outside of the barrel never gets much hotter than 100 to 200 degrees F for most civilian firearms. But for those few milliseconds the surface of the metal becomes so hot that it can literally be washed off by the passage of the bullet.
 
Yes, those few milliseconds the surface of the metal becomes so hot that it can literally be washed off by the passage of the bullet.

And the greatest amount of friction between bullet and barrel is where the leade engraves the bullet at the origin of the rifling. Pressure's almost the highest at this point, too.

.308 Win barrels erode away at the origin of the rifling at about .001" for every 40 rounds fired. 30 caliber magnum barrels erode that much every 15 shots. My .264 Win Mag barrel leade advanced down the barrel about .001" every 7 shots. Bullet jump to the rifling increases these amounts for a given bullet and cartridge overall length.
 
Assuming you get the barrel red hot, I imagine continuing to shoot would at the very least accelerate the decay of the rifling.
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Well, isn't that the idea behind chain guns? They shoot so fast that they need to rotate the barrels or else they'd destroy themselves.

Although I still find it doubtful that you could significantly overheat the barrel with just a couple mags.
 
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Chain guns were made to increase the rate of fire. The extra barrels each shoot a round while one barrel's reloading.

They also eject duds so the weapon keeps on firing; the main reason they came about in the first place. They don't rely on ammo to power the mechanisms.

"Chain gun" is a registered trademark of Orbital ATK for "externally-powered machine guns".
 
There seems to be some confussion about "Chain Guns"....

The chain gun is an externally powered gun that uses a chain, much like a bicycle chain, to move the bolt back and forth to cycle the action. They only have one barrel, and, actually, have very moderate rates of fire, 350 to 600 rpm.

They were developed by Hughes back in the early 1970s.

There are many types of 'externally powered' machine gun, some have a single barrel, some have multiple barrels. The reason you have multiple barrels is the simple fact that the time required to move the bolt back far enough the extract and eject the spent cartridge, feed, lock and fire a new cartridge limits the rate of fire to around 1500 rpm. If you want a faster rate of fire, you need to be doing some of these operations at the same time, which means you need multiple barrels (Gatling type), or multiple chambers (revolver type). Also, at 1500 rpm, the stresses on the the case, and reciprocating parts are extremely high, In order to make a lighter gun, you need to slow the speed down, but to keep the high RoF, loading and firing need to be done simultaneously.

Also, the M61A1, GAU-8, GAU-12, M197, etc are externally powered, but all Gatling type machine guns are not necessarily externally powered, the Russian AK-630 is a self-powered Gatling type machine gun with a RoF in the 6000 rpm range, as was the gun in the SUU-23/A gun pod (a modified M61A1).

The GSh-23 is another example of a multiple barrel, self-powered (gas) machine gun, this time only two barrels, with a very high RoF, around 3500 rpm.
 
Bart B. said:
[Rotary, or Gatling type guns] also eject duds so the weapon keeps on firing; the main reason they came about in the first place. They don't rely on ammo to power the mechanisms.
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Actually, that is a big drawback, the fact that the bolt unlocks, not because the cartridge has fired, but because the the barrel is in unlocking orientation.

Q: What happens if the the cartridge takes a fraction of a millisecond longer to ignite than normal?

A: Something catastrophic, that's what.

For this reason, ammunition made for use in externally powered guns has very tight requirements on action time, the time it takes from initiation of the primer to bullet exit.

The early Hughes (now-ATK) Chain Guns in M2/M3 Bradleys had at least one case of a slow action time round going off after the bolt was unlocked, but still in the chamber. It damaged the gun and injured the gunner. The design was modified to have a recoil-interlock. Now, if a sensor on the receiver does not sense a full recoil by a certain time after dropping the firing pin, power to the drive motor is cut-off.

The all Gatlings do not have this option, as you can't just stop 200 pounds of spinning steel in an instant. And, at least one type of ammunition was deemed "war-use-only" due to the fact that they could not guarantee that it would not hang-fire and cause a safety issue, and is not authorized for manned mounts.

A self-powered Gatling in the SUU pod can burp through about 20 duds in a row before it looses enough steam to stop firing. What are the chances of getting 20 consecutive duds in a belt of ammunition? Next to nothing.
 
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For rifles normally used by us civilians, accuracy is reduced mostly from erosion of the leade. The main length of a barrel is rarely "shot out". Erosion of the leade can happen faster with sustained rapid fire, as compared to a slower rate with pauses between shots. The area around the leade doesn't have as much time to cool down in rapid fire.

Think of it this way: A cutting torch doesn't work with only brief applications of its heat. Sustained application cuts.
 
I recall an old buddy who was a WW2 PTO P-51 pilot telling me that they were instructed to fire their .50's in short bursts.
He relayed a story to me in which he, after a bomber escort mission, engaged a Japanese train. He said "You can't imagine how difficult it was to hit a train traveling 50 mph from an aircraft traveling 375 mph." He went on to say that in his determination to take out the train, he fired long bursts and subsequently burned out the barrels of all six of his machine guns. This in turn resulted in a sound butt chewing.
So, from that I'd say there is truth to the subject.

35W
 
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35 Whelen said:
I recall an old buddy who was a WW2 ETO P-51 pilot telling me that they were instructed to fire their .50's in short bursts.
He relayed a story to me in which he, after a bomber escort mission, engaged a Japanese train. He said "You can't imagine how difficult it was to hit a train traveling 50 mph from an aircraft traveling 375 mph." He went on to say that in his determination to take out the train, he fired long bursts and subsequently burned out the barrels of all six of his machine guns. This in turn resulted in a sound butt chewing.
So, from that I'd say there is truth to the subject.

35W
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But did he get the train? Inquiring minds want to know.
 
If the barrel changes color (turns white or brown, burns all the oil off), you have it hot. Lots of people think that just because they cant touch it, its hot. Heck, I cant touch black paint on my car in the sun, doesnt mean its damaging the steel...

Yes, if you get the barrel truly hot, you can damage it in fairly short order. This is assuming its a semi auto.
 
It definitely does that; I had an M16A1's barrel glowing to the point my Assistant Armorer lit his cigarette off it. (This was from firing up excess blanks from an FTX), and when I shot it for live fire, it was remarkably worse. (I was planning on changing it anyway, that's the only reason I let it get red hot. I wanted to see how bad it wrecked the accuracy.) After I replaced the barrel and rezeroed, it was back up to the usual poor M16A1 standards. (When compared to the A2.)
 
35 Whelen said:
I recall an old buddy who was a WW2 ETO P-51 pilot telling me that they were instructed to fire their .50's in short bursts.
He relayed a story to me in which he, after a bomber escort mission, engaged a Japanese train. He said "You can't imagine how difficult it was to hit a train traveling 50 mph from an aircraft traveling 375 mph." He went on to say that in his determination to take out the train, he fired long bursts and subsequently burned out the barrels of all six of his machine guns. This in turn resulted in a sound butt chewing.
So, from that I'd say there is truth to the subject.

35W
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What were the Japanese doing in the ETO?

(Inquiring minds want to know.)
 
35 Whelen said:
I recall an old buddy who was a WW2 ETO P-51 pilot telling me that they were instructed to fire their .50's in short bursts.
He relayed a story to me in which he, after a bomber escort mission, engaged a Japanese train. He said "You can't imagine how difficult it was to hit a train traveling 50 mph from an aircraft traveling 375 mph." He went on to say that in his determination to take out the train, he fired long bursts and subsequently burned out the barrels of all six of his machine guns. This in turn resulted in a sound butt chewing.
So, from that I'd say there is truth to the subject.

35W
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Seeing as the P-51 only had 380 rounds per gun on the inboard pair and 270 rounds per gun for the outer four, I don't see how he could have burned up all six his barrels.... maybe (but I doubt it) the inboard pair in a single 380 round burst, but 270 rounds in a single burst through the lighter AN/M2 barrel shouldn't permanently damage it. It wouldn't do it much good, but not burn it up.

The reason they told pilots to use short bursts was to conserve ammunition. The AN/M2 aircraft machine gun had a higher rate of fire than the ground version, the M2 HB, for a aircraft gun a 270 round belt equals 20 seconds, 380 rounds - 27 seconds.

Probably got the butt chewing for a) not getting the train, b) using up all his ammunition too early in the mission and only on one train, or c) both.
 
lysanderxiii said:
Seeing as the P-51 only had 380 rounds per gun on the inboard pair and 270 rounds per gun for the outer four, I don't see how he could have burned up all six his barrels.... maybe (but I doubt it) the inboard pair in a single 380 round burst, but 270 rounds in a single burst through the lighter AN/M2 barrel shouldn't permanently damage it. It wouldn't do it much good, but not burn it up.

The reason they told pilots to use short bursts was to conserve ammunition. The AN/M2 aircraft machine gun had a higher rate of fire than the ground version, the M2 HB, for a aircraft gun a 270 round belt equals 20 seconds, 380 rounds - 27 seconds.

Probably got the butt chewing for a) not getting the train, b) using up all his ammunition too early in the mission and only on one train, or c) both.
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I wondered how long it would take for a post like yours come up.

I guess if he were still alive you could ask him that question. I knew the guy well and know he had nothing to prove. In fact he only told the story after I inquired about his experience as a combat pilot.

I only know what he told me. If you know more about this person and his experiences, I'm all ears.

35W
 
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