How hot is too hot for a barrel?

When the muzzle begins to sag...



Unless you are dumping mag after mag of full auto fire, I dont think I'd worry too much.  And if you are you need to spread some of that ammo wealth!  The barrel will obviously get too hot to hold quick, and the handguards may even get warm.  I've never even noticed mine get very warm, unless again I'm really rippin out some rounds over an extended range session.  

Why do you ask??  Any problem?  Do tell...


-Hershey

Depends upon the bbl.

I have ssen bbl's that are okay after some prolonged shooting with a can that made the bullets goo...

I once saw an 11.5" barrelled gun get so hot the front sight housing expaned and the taper pins started working out.  


That was too hot

My rule is that when the glue in the handguards starts burning, it is time to switch rifles and let that one cool.

Quoted: How hot is too hot for a barrel?

when the rifle fires by his own (<--- sorry for bad english, hope u understand)

I think you'll have rounds cooking off followed by the gas tube melting. That's what I've seen happen after the third Beta mag is inserted on a continuous full auto dump.

I really think that the Chrome lining is compromised when you see the barrel turn red.

With M4 barrels that happens pretty quick like 150rds in 2minutes.

The worst they'll get is about 5MOA at 100yds though.  That's after they see about 300-600rds in around 5minutes.  At that point half the barrel will be red.  My best guess as to why the accuracy deteriorates, is that actuall bore is far hotter and the Chrome strips out.  After that you'll notice that the barrel won't clean easilly anymore either (2-5 patches to clean turns into 50-100).

If you are worried about it, it's probably good to have one abused upper and one accurate one.

Basically if you keep the selector on semi, and take aimed shots you should be able to go through 10-12 30rd mags without damageing the accuracy of the barrel.

I say that because most people fire far more than 15rds a minute even on semi-auto-- more like 40-60RPM for most guys in aimed semi-auto fire.  If you have the discipline to fire 15RPM or less, or have a situation in which there are few enough targets to warrant it, you should technically be able to fire as many rounds as time allows.  I've never done a test of that but it's probably true.

Gas tube will melt first.

Quoted: Gas tube will melt first.

Yes it will.

Been there, done that.

-J

Quoted: Gas tube will melt first.

That's why guns like the AK and FNC are so great; I've seen AK handguards catch on fire and FNC handguards get soft but the gun is still firing, no gas tube to stop the fun.

I thought Gas tube worked like a fuse to prevent serious barrel damage...and it was a good thing.

They could have made gas tube out of same material used in making the barrels.

"That's why guns like the AK and FNC are so great; I've seen AK handguards catch on fire and FNC handguards get soft but the gun is still firing, no gas tube to stop the fun."

The AR gas tube is not a very good fuse in my opinion.  I have seen 900rds through an M16A2 in about 10minutes, and the barrel got red hot, handguards started to melt, FH came off and went down range, and the gas tube was still intact.

That's why there are really two categories:

1: damageing the accuracy of the barrel

2: ruining the barrel

Damageing the accuracy is pretty easy (like I said 400-500rds fired fast can do it.)

After you screw up the accuracy, it levels off at about 4-5MOA and then you can abuse it as much as you want with almost no deterioration, unless of course you fire enough to make the barrel droop, at which point it is totally destroyed for all intents and purposes, something I have never seen done.

To me, 4-5MOA is about as "ruined" as a barrel can get. that's pretty piss-poor perforemance.

I wouldn't worry about catastrophic failure or barrel droop without a suppressor attached, because basically you have to try really hard to get them to occur.

anyone got a video of some AR torture.

It's probably time to take a break when you can light cannon fuse on contact with your muzzle.

After you screw up the accuracy, it levels off at about 4-5MOA and then you can abuse it as much as you want with almost no deterioration

Yes, basically you've gotten the heat high enough in the chamber that the throat has eroded badly. You can sometimes squeeze a little extra accuracy out of those barrels by changing to a bullet with a different ogive so that it contacts at a different point on the throat.

That will give you acceptable accuracy again until the throat wears in that spot also (which will happen a lot faster).

"Yes, basically you've gotten the heat high enough in the chamber that the throat has eroded badly. You can sometimes squeeze a little extra accuracy out of those barrels by changing to a bullet with a different ogive so that it contacts at a different point on the throat."

The only thing that doesn't explain is why it suddenly begins to take 50+ patches to clean the bore (if you want a patch to come out clean, which you will quickly give up) when it took 2-4 when the bore was new.

The only thing that doesn't explain is why it suddenly begins to take 50+ patches to clean the bore (if you want a patch to come out clean, which you will quickly give up) when it took 2-4 when the bore was new.

Heat checking in the throat - the metal develops little cracks like a dry lake bed from the heat and then the metal begins to flake off with the friction and gases, leaving a much rougher surface underneath that collects powder and other goop quite nicely.

When the front hand guard begins to visibly smoke and there is the distinct smell of burning wood; when the linseed oil starts boiling out of the wood, smoking and burning; when the front handguard is charred wood on the inside - THAT'S TOO HOT!

Oopps!, sorry, I forgot we are not allowed to discuss M1 Garands here.  My bad  

Hell, I thought when the handguards started to smell like burning plastic it meant the rifle was finally warmed up for real stress testing!

Back in my days in the guard a small group of us went to the pop-up range at night with all the unit's extra ammo, a footlocker full of mags, and 12 A1s that the unit was turning in.

Each of us had 30 plus mags on the line, and we started shooting full auto at the targets as they cycled over and over.

I had my leather gloves on, and not being totally stupid I also had shooting glasses on. As time went on I had to be quick about getting from the bolt release to the trigger because of cookoffs. The barrel got so hot that I could see to do mag changes from its bright red light.  The rifle was so hot that I had to hold the front of the magazine to fire, and even with the gloves my hand got way too hot. (this was with A2 handguards w/shields)

I had put on a good coat of CLP on the bolt and BC of the rifle, and she kept chugging until the end.

The bore was ragged inside and we ended up cleaning the guns in the motor building's cleaner, and the gas tube was wavy but not melted. The barrel coating and the tube surface were quite damaged.