How many rounds could you shoot before the barrel over heats? I'm thinking of a rate of fire of about 2 shots a second. Pretty fast shooting. I know the barrel gets hot. Has anyone overheated their barrel? I'm just wondering, for example. I'm guessing 60 shots in 30 seconds would burn something up.

Just got home from a CMP match. After shooting ten rounds in 60 seconds we like to let the rifles cool until you can wrap your hand around the gas block and hold it there. It's fairly cool on the AR's immediately, but the M1A's and Garands are too hot to hold for maybe 15 minutes.

I personally would not choose to shoot more than 30 shots in a minute. Remember heat is the enemy of barrel steel.

Heat in an AR barrel that you will tolerate is relative to the purpose at hand. In combat, shoot away, and if it gets too hot to hold, pour water down the breech and resume.

The main damage is done in the barrel throat. As the barrel overheats, the surface of the throat starts to look like dried mud, and minute pieces start to flake off. As the throat erodes, the rifling disappears from the chamber forward. I've seen old military barrels with no rifling for 3 inches forward of the chamber but would still hold 3" at 100 yds. Disastrous loss of accuracy for a match rifle, but would still keep Charlie off your back.

So how often do you want to buy a new barrel, and what accuracy do you need? Steel that is too hot for your hand to hold is being damaged a little at each shot.

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Science plus Art

Sustained rate of fire as defined by the military is quite low. Mag dumps are way over this figure. I do not recall the exact figure, but is very easy to look up if you want.

As mentioned above, "emergency use" obviously over rides proper care and use of the weapon.

Just for informational purposes, per this website, M4 Carbine | Marines.com, sustained rate of fire is 12 to 15 rounds per minute, for both M16 and M4's.

At the range yesterday, I watched a guy dump a 100 round drum in about 30 seconds (or less, I'm guessing) on full auto. He did this 3 times while I was there. I wonder how his barrel is holding up.

Pretty sure it can take more than you can give it.

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Freedom isn't free.

Wow! I think I counted 26 mags on full auto. 780 rounds?!!!?

Gee, I wonder what lube he was using?

Pretty sure the lube was all gone by the 6th or 7th mag. If you listen closely you can hear the cyclic rate getting slower.

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Freedom isn't free.

Several people have noted the ill effects of heat buildup in the barrel. Basically, if you dump 10 30 round mags, that barrel has been damaged. It's life and accuracy has been degraded.

Now, can you do that sort of thing if you're facing a human wave attack? You betcha. But in that case you have more exigent worries than barrel life.

Eh... shoot it how you want. The ammo is a bunch more expensive than a new barrel. You can get new barrels for not much over $100.

Better his gun than mine...

Take a look at the video in the upper right had corner when the posted video finishes. "The Ultimate AR 15 Melt Down. 850 rounds before the barrel burst. Interesting analysis of the wear.