I was sitting in a budget meeting today, daydreaming about ar15.com, when I thought about a little warning in my bushmaster manual.  It warned about keeping a round chambered in a hot barrel, for fear that it could fire due to the heat of the barrel.

And for that matter, anyone ever have a misfire, eject the round only to have it fire minutes later?

MG

Happened in the .50 cals I shot out of the side of Helicopters, but then again we abused them to the point of have rounds come out the sides of the barrel.

I seriously doubt ya could shoot a semi-automatic AR15 long enough or fast enough to worry about cook-off, now with a FA rifle......... that's a different story.

As to your second question.....

The only way this round is going off is IF you didn't wait long enough "after the mis-fire", which is standard safe operating procedure for a dud round. It can't go off from cook-off AFTER it's left the chamber, IMO.

Should you have a dud round, ALWAYs wait "with rifle pointed in a safe direction" a minute or so incase ya got a slow primer burn or other problem.....

Then eject the round and toss it into the local dud bucket at your range.

Mike

Night fire range, basic training, SAW.  Round jammed in the chamber on the last firing order, line was cleared, we were moved into the grandstands which happened to be right behind the weapon in question. Round cooked off with the cover up and threw debris into the eye of our CO. All of this happened right in front of us.

I've had a M4 cook off a round after firing several hundred rounds in a few minutes.  The weapon was so hot that smoke was coming off the glue in the handguards, my sling was melting and I had to hold my forward hand on the base of the magazine to shoot, the handguard and magazine well was too hot to touch.  I could've used a forward vertical handgrip!

It's pretty sobering when you let the bolt go forward and the round fire before you even put your finger on the trigger.

Makes you glad you're practicing good muzzle awareness and reinforces to do it in the future.

In the Guard the M60 I was on would get so hot it just kept on firing until the belt ran out... Had to lean on it just to keep it from taking off and flying away. I would have broken off belt if it had been much longer but I never had more than 20 or so rounds left every time this happened. Fun Stuff!

Doing a break-in of some department M4's.  Very hot day, about 400+ rounds fired within a few minutes, chambered a round and sat there with the barrel facing the target for a minute and BOOM!

Scared the shit out of me.  I immediately unloaded it and let it cool off.

Nah, not a problem for us civvies

Quoted: Doing a break-in of some department M4's.  Very hot day, about 400+ rounds fired within a few minutes,

That is an "aggressive" break in procedure lol.

Quoted: Night fire range, basic training, SAW.  Round jammed in the chamber on the last firing order, line was cleared, we were moved into the grandstands which happened to be right behind the weapon in question. Round cooked off with the cover up and threw debris into the eye of our CO. All of this happened right in front of us.

I had the same thing happen to me. Except I was the one that got all the shit in the eye.

At Camp Pendleton my engineers co. was familiarization firing several M60s and a couple of Ma Duces, all on tripods. We were all on the same firing line shooting across a small canyon at 50 gal. drums on the opposite slope. I was acting as the assistant gunner, feeding the belt (facing the left side of the MG), with my back to an M60. The guy on the trigger behind me paused for a minute and BANG! The round on the platten cooked off, the split case hits me in the ass. I near pooped my pants. I thought I had been shot. Left a nice welt.

Everyone knows tracers will start a grass fire, but did you know concentrated full auto fire will put out a grass fire?