AR 15 sustained rate of fire

[Glenn]

The owners manual for my Olympic Arms AR15 says that the AR 15 can sustain a rate of fire of only 12 to 15 rounds a minute. It also warns that as few as 140 rounds fired quickly can cause the rifle to "cook off" or fire a round from heat only. I have seen quite a few guns fired until they were very hot and have never seen one cook off. Is that something to worry about? I am aware that overheating a gun is a good way to shorten its life and don't plan to shoot hundreds of rounds that quickly but 12 to 15 a minute seems awfully slow.

Glenn

[Reservoir Dog]

I guess a cook-off is a possibility, although, in all my years of shooting, I have never seen one.

Recently, I went through a carbine training class, and in some of the drills, we would go through 5 or 6 30rd mags in the span of a few minutes. The instructors advised us that (if we felt it necessary) to lock back the BCGs on our ARs, to let the barrel ventilate after these drills. I never did it, and never had a problem.

My guess is the 12 to 15 limit is just "lawyer speak" they put in the manual.

[thundersnow]

+1 for muzzle safety.

I am sure it will be unpredictable and vary with each gun, ammo, outside temp, and any number of other conditions. So when the zombies are at your door, switch to your side arm for a few while the barrel cools off...

----

Schweizerische Industrie Gesellschaft (SIG) P229 and P6 /// Ruger Target 10/22

[DaveTN]

It can happen. Those numbers and times they are using supposedly come from an Army Technical Manual on the M-16.

There are videos out there of it happening. If you fire hundreds of rounds quickly and then leave a round in the chamber; it can cook off.

I don’t leave a round in the chamber after a single mag dump.

[Guest The Dude]

i always thought that the practical rate of fire would be around 30 rounds per minute with nothing to worry about? thats prolly stated for liability reasons. of course there are always the poeple that dont use common sense with firearms wich is why there are so many things stated in the manuals now days.

[Glenn]

I guess most times the gun is empty after firing until overheated. I got a very large blister from touching the barrel of a BAR after it had fired 5 or 6 mags in a few minutes but it was always empty when the firing was stopped.

Glenn

[Dolomite_supafly]

I have caused rounds to cook off. It was when I was in the military and at the end of the fiscal year. We were shooting up ammo to keep from loosing our allocation. I fired about 7-8 mags on full auto then it began cooking off rounds. It stayed hot enough that it would cook a round off every 1-2 seconds.

Not sure about sustained rates of fire.

Dolomite

[Guest The Dude]

i think its safe to say as long as you dont do back to back mag dumps, then you should be good to go.

[c.a.willard]

As Dave said the 12-15 rounds per minute, comes from the Army TM, that 12-15 rounds is supposed to be what the rifle can do indefinately, ie you could fire 3000 rounds at a rate of 12-15 per minute without inducing enough heat to cause a catastrophic failure. I wouldnt worry about overheating much unless your planning on doing several consecutive mag dumps.

[R1100R]

I cooked off a tripod mounted M2 .50 cal once. One round cooked off in the brass pile and another in the chamber. Scared the @#)&^ out of me. It was at dusk/twilight and I could see the barrel glow.

I have seen M16's cook of rounds to include a M60 many times.

Edited February 18, 2012 by R1100R

[Dolomite_supafly]

I cooked off a tripod mounted M2 .50 cal once. One round cooked off in the brass pile and another in the chamber. Scared the @#)&^ out of me. It was at dusk/twilight and I could see the barrel glow.

I have seen M16's cook of rounds to include a M60 many times.

How do you cook off a round in a M60?

If fires from an open bolt so there is no way to chamber a round without it firing the round. You cannot chamber a round without firing it. You cannot just chamber a round. It will never be in the chamber long enough to cook off because they are designed to fire the instant the bolt closes.

Again, a cook off is not possible with a M60 or any other weapon system that fires from an open bolt.

Dolomite

[kwe45919]

^^ That's what I thought after I read his post. I didn't think open bolts could "cook off " anything.....glad you posted....reconfirmed it for me.

[R1100R]

Dolomite.,

I forgot your Subject Matter Expert. I've been Soldiering a long time, I'd be careful before you call someone out......Next time Man Up and take it to a Personal Message and ask a question. This is the second time you have done this to me. When I disagree with something you have said I let it go.

As usual your wrong on some things. I bow to your knowledge in some things though.

From a dirty weapon when locked up: Mainly seen as my time as a Drill at Ft Benning and Jackson. It is also called a run away in some circles. Chamber is hot and keeps firing. Old POS M60's for trainees with dirty and worn out firing systems. Have to break the belt to stop. i have seen single and mulitples. Give a company of trainess four weapons for Fam- Fire and anything can happen.

.

Straight out of the TM 3-22-68 Chapter 2 on the M60 ( Para number two) and 2-24.

DANGERS

1. IF NOTHING IS EJECTED AND THE WEAPON IS HOT (200 OR MORE[FIRED IN LESS THAN 2 MINUTES), DO NOT OPEN THE COVER. MOVE THE SAFETY TO "S", WHICH PLACES THE WEAPON ON "S". KEEP THE WEAPON POINTED DOWNRANGE AND KEEP AWAY FROM THE WEAPON FOR 15 MINUTES, THEN CLEAR THE WEAPON.[/color]
   
2. BE CAREFUL IN CLEARING THE WEAPON WHEN THE BARREL IS HOT, A ROUND MAY FIRE (COOK OFF) DUE TO THE BARREL'S HEAT INSTEAD OF DUE TO THE FIRING MECHANISM. DURING TRAINING OR ON A FIRING RANGE, AFTER THE WEAPON HAS FIRED 200 ROUNDS, ITS BARREL IS CONSIDERED A HOT BARREL.
   
3. DURING
   WAIT 5 SECONDS, BECAUSE OF THE POSSIBILITY OF A "HANGFIRE," BEFORE APPLYING IMMEDIATE AND REMEDIAL ACTION. DURING TRAINING, WAIT 15 MINUTES BEFORE CLEARING A HOT WEAPON AND APPLYING IMMEDIATE OR REMEDIAL ACTION.[/color]
   

NOTE:

When applying immediate or remedial action on a cold or hot gun, if any part of the round (ranging from the tip of the bullet to the rim) is in the chamber, the gunner removes the ammunition from the feed tray only, then closes the cover and attempts to fire. If the weapon fires, he reloads and continues firing. If it does not fire, he clears the weapon (removes the round using a clearing rod with the cover closed, not using anything other than a clearing rod), then he inspects the weapon and ammunition.

A cookoff is the firing of a round caused by the heat of a hot barrel and not by the firing mechanism. A cookoff can be avoided by applying immediate action within 10 seconds after a failure to fire. If the M60 stops firing, the gunner performs the following immediate actions. An effective memory aid is POPP, which stands for Pull, Observe, Push, and Press:

a. Pulls and locks the cocking handle to the rear while observing the ejection port to see if a cartridge case, belt link, or round is ejected. Ensures that the bolt remains to the rear to prevent double feeding if a round or cartridge case is not ejected.

b. If a cartridge case, belt link, or a round is ejected, returns the cocking handle to the forward position, aims on the target, and presses the trigger. If the weapon still does not fire, takes remedial action. If a cartridge case, belt link, or round is not ejected, takes remedial action.

Edited February 20, 2012 by R1100R

[Dolomite_supafly]

Just saying a properly functioning M60 cannot cook off a round no matter how hot the barrel is. If there are other malfunctions then it is possible but a normally functioning gun that fires from an open bolt cannot cook a round off. It is just not possible for a round to chamber and remained chambered long enough to cook off a round on a properly functioning M60.

In order for a cookoff to happen in a M60 there has to be other failures in how the weapon is functioning. Yes it can happen but not with a properly functioning weapon.

A run away gun is not a cook off, two totally different malfunctions. I have plenty of time on M60's as well and have had a gun run away dozens of times over the years.

Please feel free to link where I am usually wrong. I welcome it.

Dolomite

[R1100R]

^{Well the TM speaks for itself. Open bolt guns are less prone to cook off. There are two types of run aways. Quite a few open bolt designs have had cook offs. With a properly functioned weapon they are less likely.}

^{The discussion was cook offs not properly functioning wepons. They were all properly function weapons till the malfuction occured.}

^{That is why they are called malfunctions.}

^{From going to no it can't happen period to, Yes it can speaks volumes .. Bottom line it can happen that was the subject.}

^{I wish you well. i do enjoy reading most of your posts. I find some of your projects intriguing. BTW I don't sit on the side lines and sharp shoot, I would PM you first for a discussion/ opinion.}

Edited February 21, 2012 by R1100R

[R1100R]

Just saying a properly functioning M60 cannot cook off a round no matter how hot the barrel is. If there are other malfunctions then it is possible but a normally functioning gun that fires from an open bolt cannot cook a round off. It is just not possible for a round to chamber and remained chambered long enough to cook off a round on a properly functioning M60.

In order for a cookoff to happen in a M60 there has to be other failures in how the weapon is functioning. Yes it can happen but not with a properly functioning weapon.

A run away gun is not a cook off, two totally different malfunctions. I have plenty of time on M60's as well and have had a gun run away dozens of times over the years.

Please feel free to link where I am usually wrong. I welcome it.

Dolomite

For posterity, thank you for your response.

To the OP, I have personally never seen a cook off in a semi auto AR. I have seen a AK catch fire once during mag dumps,it still kept firing unitl it was to hot to hold.

[Dolomite_supafly]

As usual your wrong on some things. I bow to your knowledge in some things though.

Still waiting?

Please link where I am as usually wrong.

Also, you make sure to quote my post for posterity yet it seems as though you have to go back and edit yours.

Dolomite

[R1100R]

Dolomite,

I already have the post above. I edited by adding substance and to correct spelling and grammar ( I'm a horrible typist). You started the quote portion and made this personal.

You were wrong, I pointed it out and you admitted it in your way. Just let it go, you started this.

Some things should be changed to" couple" of things". I apologize to you for my choice of words.

We will just agree to disagree. I am letting this go.

I still admire how you help local people with your knowledge and experience with their weapons and I do enjoy reading about

your projects. We are all wrong sometimes.

I would like to meet you sometime just to tap your knowledge and discuss some projects. God Bless you and your Family.

I apologize to the OP for getting into this in his thread.

.

[Guest BungieCord]

a video of a guy firing an M4, rock 'n roll, as fast as he can change (30-rd) mags. He's firing ~190 RPM and the hand guard catches fire ~400 rounds. He finally gets a cook-off at ~420 rounds and the gas tube melts after firing ~810 rounds in just over 4 minutes. It still functions single shot.