question about cooking off rounds


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BlackOpsSec
March 2, 2006, 06:53 PM
i was at the range yesterday and cooked off two consecutive rounds (Winchester 115 gr white box practice/target ammo) from my XD-9 Subcompact. this happened after putting 10 rnds through the gun during a 15 sec period.

my question is: which types/styles of guns are more susceptible to cooking off rounds? short or long barreled? metal or polymer frame? large caliber or small caliber? also, which ammo is more prone to cooking off?

thanks,
kw

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Firethorn
March 2, 2006, 07:15 PM
No properly functioning gun will 'cook-off' a round. Even machine guns don't get hot enough. :scrutiny:

Cooking-off of a round requires a large amount of heat, such as tossing the rounds directly into a fire for several minutes. The mass of even a small gun is plenty enough to absorb enough heat to prevent this.

What you probably have is a stuck or broken firing pin.

What exactly happened? Did the gun fire the rounds immediatly upon the slide returning to battery or was there a pause?

rero360
March 2, 2006, 07:19 PM
well, I always believe in never saying never, but in my experience, I've shot a M2 .50cal machine gun, between me and my A gunner putting 400 rounds down range pretty much as fast as we could, then we would stop, police up brass and links and go get more ammo.

we had 6 guns going that day, pretty much non stop for about 12 hour, 2 guns broke, not exactly sure how, but we didn't experience one round cooked off.

on the other hand I've seen a number of rounds cook off in 249 SAWs, but that was when I was in basic and we were firing as fast as possible to get everyone through.

as far as handguns, I'm sure it might be possible, but I've never heard of it happening. it would be quite a feat to pull off.

Amish_Bill
March 2, 2006, 07:20 PM
Uh, machineguns DO get hot enough!

(otherwise we wouldn't have been scrambling to setup a night-time LZ for a medevac that one cold, long night.....)

15 rounds from an XD and it's discharging on it's own? You've got a Serious Problem there bud, but it's not a cookoff. There's something mechanically wrong with that pistol. Have it checked before you chamber another round!

Owen
March 2, 2006, 07:21 PM
I used to perform endurance testing on pistols. We generally used 150 16 round magazines. We would shoot those in less than 45 minutes. The pistol would get hot enough that if you touched the slide, you would leave skin behind.

We never had a cook-off.

When we were shooting machineguns, the barrels would be several hundred rounds beyond cherry red before we could induce a cookoff.

I really, really doubt you had a cook-off.

Vern Humphrey
March 2, 2006, 07:27 PM
Most machineguns and other automatic weapons fire from an open bolt -- there is no round in the chambed to cook off. Pulling the trigger releases the bolt, which chambers the round as it goes forward and fires it upon lockup. So you would NOT get a cookoff in a modern machinegun.

On the other hand, if you had a weapon like the M14E2 (the full auto version of the M14) which fires from a closed bolt -- and hence has a round in the chamber, you CAN get a cook off.

It is highly unlikely what you experienced was a cookoff. Tell us more -- exactly what happened -- and maybe we can diagnose the problem.

.45Guy
March 2, 2006, 07:28 PM
on the other hand I've seen a number of rounds cook off in 249 SAWs, but that was when I was in basic and we were firing as fast as possible to get everyone through.


249's fire from an open bolt, seems like an unlikely candidate for a cook off.

Firethorn
March 2, 2006, 07:34 PM
Ok, I'll amend my statement. Under Normal operation, not including stress tests or equivalent, even machine guns do not cook off their rounds.

You're generally risking your barrel as well if you're getting the thing hot enough.

Edit: No matter what else is said here, I seriously recommend you take your pistol to a gunsmith for a detailed tear-down and inspection.

Owen
March 2, 2006, 07:39 PM
We induced with a cartidge with a dummy primer

We used a thermocouple to make sure we were above a certain temperature, which escapes my memory at this time.

NATO D14 has a requirement that machineguns don't grenade (no fragments projected from gun) in a cook-off situation.

Owen
March 2, 2006, 07:46 PM
Oh yeah,

BlackOpsSec, get thee to a gunsmith!

BlackOpsSec
March 2, 2006, 10:03 PM
thanks for all of the excellent replies, folks. the rounds discharged right after the slide returned to battery. a trip to the gunsmith is in order. :)

MedGrl
March 2, 2006, 10:30 PM
Please forgive a Newbie question...but what does "Cooking off a round" mean? I gather it meand the gun discharges without the triger being pulled. But how?

rero360
March 3, 2006, 12:45 PM
.45guy, my bad, was thinking of run away guns with the 249s, it was a while ago.

HerrWolfe
March 3, 2006, 12:55 PM
Not sure about cookoff in a pistol but had one in NM M1 on the 600 yard line at Perry, years ago, and only one I ever had. Was maybe 3/4 through the 20 shot string, hot enought to fry the proverbial egg, closed the bolt and bang, had not even shouldered the weapon, but again it was slow fire of course. Did I say it was hot; it was blazing hot. Never had a problem with that M1 before or after, and it had the standard trigger pull, 4 1/2 lb if I remember correctly. Really doubt that the pistol had a cook off unless you were firing in high heat and had round after round after round, and then I really doubt it. If there was a different explanation for the firing, I never heard it. Seems it would not have gone off that fast but taken time to get up to temperature. Maybe someone has information on what else could have caused it.
And yes, cook offs do occur regardless of what some may say. Think that they were even mentioned in the army training manual that was used for newbies back then. A real learning experience why one should never point a gun in the wrong direction.

rms/pa
March 3, 2006, 01:01 PM
medgrl".but what does "Cooking off a round" mean? I gather it meand the gun discharges without the triger being pulled. But how?"

this is much more common in cannon or naval rifles, each round fired heats the barrel/tube and housing. this residual heat will build up to ignition temps over time. say 40 rounds fired in a 5 minute period puts you in hazard range.

there are time vs rounds fired charts that show roughly how likely a cook off is. this is usualy not a hazard unless you have a function casualty leaving a round in the tube with an open breech.

if the breech is closed just keep the weapon pointed down range and go have coffee till it fires.

the open breech scenario is "leemer " time. its why gunners retire early.

in the really unlikely event the projectile cooks before the powder case. dependents will collect insurance. and the mount will not be very usefull till after a long yard period.

rms/pa

Husker1911
March 3, 2006, 01:10 PM
Medgrl, you're aware just how hot a gun can become from repeated, frequent firing, especially with little time between rounds. This is especially prevalent on submachine guns. The chamber surrounding the loaded cartridge becomes so hot the heat transfers to the brass cartridge, and if it's hot enough, induces the powder or primer to fire, seemingly on its own! That's why so many submachine gun designs utilize an open bolt. If you're unsure about what an open bolt design is, please ask. Hope this helps!

MedGrl
March 3, 2006, 02:08 PM
thanks Husker1911 and rms/pa. That explained the holes in my understanding quite well. Thanks.

Jim K
March 3, 2006, 02:15 PM
Well, I would say that most SMGs use open bolt firing not to prevent cook-off but because it is simpler and advance primer ignition allows the use of a light bolt and recoil spring.

But a pistol fired only 10 rounds in 15 seconds (or even in 3 seconds) certainly should not cook off; there has to be some other explanation.

Jim

Amish_Bill
March 3, 2006, 02:38 PM
The part where he says the round fired as soon as the slide slammed home makes me think Slam Fire instead of CookOff.

Check the slide. If you can, remove the firing pin and make sure nothing is stuck in the firing pin channel. If there's nothing obvious, CALL SPRINGFIELD! They will be VERY interested that one of their pistols is slamfiring!

JAG2955
March 3, 2006, 03:14 PM
Doubt it "cooked off". Was the trigger fully released during this time? If it was pulled slightly, right above the breaking point, if might have fired due to the movement of the gun.

Kinda like bump-firing

See worthless add-ons, such as "Hellfire trigger", etc.

Taurus 66
March 3, 2006, 03:15 PM
I don't have time to read all the responses here, so if this idea has already been mentioned, please disregard.

Check the primer for indentation caused by the firing pin. If no ding on the primer, you had cooked off a round. A ding will have something to do with the firing pin or other mechanism.

my question is: which types/styles of guns are more susceptible to cooking off rounds? short or long barreled? metal or polymer frame? large caliber or small caliber? also, which ammo is more prone to cooking off?

Machine guns or fully automatic gun, of any caliber, perhaps?

JohnKSa
March 3, 2006, 11:40 PM
Mechanical problem not cookoff.

Medgrl,

Cookoff with a semi-auto pistol is theoretically possible, but you'd have SERIOUS problems operating the gun LONG before it got hot enough to cook off rounds. You would need LOTS of loaded magazines and some shooters with thick gloves (to keep from getting burned) to make it happen.

It's slightly more possible with a semi-auto rifle, but again, you'd need to really work at it. It's not something that's going to happen without some serious effort.

gezzer
March 4, 2006, 02:13 AM
More likley a stuck forward firing pin.

2-250 rnd bels and my 1919A4 WILL COOK OFF!!!!

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