I'm going ask a dumb question: Can handguns actually fire without the trigger being pulled?

[GreatGazoo]

I see news stories all the time that say "the gun went off" or something similar that leaves any human activity out of the act of firing the gun. So how common is it for a gun to just fire at a random time ? Is there any kind of temperature change, like leaving your gun in the sun or in a hot car that will make it fire? or anything else ?

[NaturalHigh]

1. Yeah, but I don't think it's common.

A fire could cause it, or a defective firing pin if the gun is dropped or shaken violently maybe.

[PoliticAverse]

2. Guns with exposed hammers can sometimes fire if the hammer gets hit

accidentally if the gun say is dropped and strikes the ground, or the hammer can be accidentally
caught on something and be pulled back and then fire the gun (this can happen sometimes
when someone puts their gun in their pants pocket).

[NaturalHigh]

4. "this can happen sometimes when someone puts their gun in their pants pocket"

Which would probably explain why I've never put a loaded (or unloaded for that matter) gun in my pants pocket.

[spin]

19. I've carried a S&W model 642 snub nosed revolver in a pocket holster for 20 years. ...

Since it's a modern revolver it wouldn't fire if dropped on a hard floor. Fortunately I have never had that happen.

I put the revolver in its pocket holster and then drop both into my pants pocket. The holster is designed so that it stays in your pocket when you draw the weapon. Of course the revolver does not have a manual safety like many semiautomatic pistols but the long and heavy trigger pull make an accidental discharge extremely unlikely especially if you "keep your bogger hook off the bang switch."

[doc03]

3. It can happen if the gun is dropped n/t

[DonP]

5. Short answer, no, modern guns have built in safety mechanisms like hammer blocks etc.

In other words, there's piece of solid steel between the hammer and the cartridge, that only comes down when the trigger is pulled.

Slightly longer answer, older gun designs (circa 1873 vintage and some modern replicas) can go off if dropped on a hard surface with a round in the chamber. But that's not "Just going off".

But normally when someone says "It just went off" they actually had their finger on the trigger and didn't realize it.

That's what is called a "Negligent Discharge".

Pay attention to the 4 safety rules and it's not a problem:

1. All guns are always loaded
2. Don't let the muzzle ever point at anything you don't wish to destroy
3. Keep you finger off the trigger until on target and ready to fire
4. Know oyu target and what is beyond it

[uppityperson]

6. It can go off without the trigger being pulled on purpose

People can and do accidentally pull the trigger and that is what it seems is often meant when "the gun went off".

[Eleanors38]

7. I don't think a modern revolver has ever fired without trigger action...

All double action revolvers made over many decades have "action bars" (or their equivalents) which prevent impacts to the hammer from in turn impinging on the firing pin, or prevent the hammer-mounted pins from striking a cartridge. In other words, there is no reason to leave a cylinder chamber empty so that the hammer may rest over it safely. Others may speak to semi-auto pistols.

On edit, the now-defunct Iver Johnson Arms & Cycle Works patented the "Hammer-the-Hammer" transfer or action bar for its revolvers in 1896.

[gejohnston]

8. extreme heat, like a fire

dropping very old or junky (like cheap two shot derringers) might. The most famous for it was the Type 94 Nambu. I have only heard of it happening with older long guns, although I do know a guy that dropped his M-16 and it went off. Fortunately, it was blanks and MILES gear, so only the laser hit the side of the tent.
Most of the time, 99.9 percent, it is something like having it in your pocket without a holster or something covering the trigger guard and having other stuff in it or trying to explain away negligence. Most of the "went off while cleaning it" is covering up negligence or stupidity.

[Travis_0004]

9. It is very very rare

In a properly functioning gun, it should not go off. What happens is people accidently pull the trigger when they did not mean to.

One important safety tip is if you ever drop a gun, let it fall. There is no danger from a modern gun falling on the ground, but if you try to catch it, it is easy to accidentally squeeze the trigger as your are catching it.

Old revolvers (mostly pre 1900) were very dangerous when dropped. Even though the guns held 6 shots, people would often not carry a round under the hammer for safety reasons.

Remington had to recall a bunch of guns (model 700) because the trigger design was faulty and could cause it to go off so bad designs can happen, but they are rare

Ammo will not cook off in a hot car, even in death valley in July. If the car caught on fire, then it could cook off, but it would have to be at least 300 degrees or so.


So to answer your question, when a gun 'accidentally goes off' I woudld say 9999 times somebody has pulled the trigger, and 1 time there was a something faulting with the gun that allowed it to happen.

[Nuclear Unicorn]

10. Gun knowledge translates into gun safety and gun safety is never dumb.

[Duckhunter935]

11. Most likely not

Possibly a worn older weapon. Any weapon in the last 30-40 years should not. Glocks and some others only have a trigger safety.

[sarisataka]

12. Actually a very good question

which has been well answered already.

I have been around guns for over thirty years and have seen well over a million rounds fired, many thousand by myself. In all of that I have seen exactly two guns fire without the trigger being pulled.

1- an old machine gun fired one round while being loaded- cause a badly worn part the armorer overlooked during inspection

2- an M-16 cooked off one round in desert heat at the end of an intensive fire exercise. The barrel was so hot it ignited the powder in the cartridge. The operator immediately unloaded the weapon, preventing further cook offs.

In both cases no one was in danger because the weapons were pointed n a safe direction.

[GreatGazoo]

13. Thanks for that answer

I have owned several guns for decades but do not claim to be any kind of expert. I lived in NYC for many years and left my guns in another state to avoid the permit issues -- they are collectible guns, not for defense. For example one is a classic Colt #3 Derringer that I inherited from my mother. I got my gun safety training as a child, mostly Y-Camp, Boy Scouts and deer hunts. Appreciate your answer (and all those of all other DUers).

[Matrosov]

14. Rarely

A firearms has to have a serious mechanical defect to just "go off." Ninety-nine times out of a hundred, someone pulled the trigger.

Even in the very few cases where I heard of a gun going off due to a serious mechanical defect, it was pretty much always caused by someone attempting DIY gun smithing.

[Straw Man]

15. As you've seen ...

... in the responses, the answer is "No," for the most part. Despite the calumny heaped on them from some quarters, gun manufacturers have gone to great lengths to design guns that will not do this. Gone are the days when a single-action revolver had to be carried with only five rounds loaded and the hammer down on an empty chamber.

Usually when people say "It just went off," they are reacting to the sudden awareness that they have fucked up badly, and they are trying desperately to avoid the consequences of their negligent or malicious behavior.

[ileus]

16. Just sitting....I'm gonna bet the farm on NO.

Now if they don't have a drop safety and are dropped or thrown....maybe.

[benEzra]

17. Generally no.

Some old designs (think antique revolvers and some antique semiautos) could go off if they dropped and fell on the hammer a certain way, or some older semiautos fell pointing straight down so that inertia could move the firing pin hard enough to discharge a shot into the ground on impact. In the 19th century, revolvers were often carried with an empty chamber under the hammer to render them drop-safe, but that is not necessary with most modern designs. Modern handguns incorporate passive safeties to prevent accidental discharge, and most could be thrown off a building onto pavement and not go off, though some mid-century designs (like the Walther PPK and the Phoenix Arms Raven) require the manual safety to be on.

Ammo can go off due to heat if the temperature of the powder exceeded its ignition temperature, but that would be around 300 degrees, give or take 10%. You can achieve that in an oven, or in a fire, but not by leaving it in a car with the windows up.

Nearly 100% of the "the gun just went off" stories you'll hear involve accidentally pulling the trigger, usually either as the result of carelessly putting a finger on the trigger when the shooter did not intend to fire the gun, trying to catch a falling gun (don't, it's drop-safe but a snatch can pull the trigger), or accidentally pulling the trigger while holstering. It's a fundamental rule of gun safety that your finger goes on the trigger only when you are about to shoot, and one of the easiest ways to identify a total n00b is to see whether they casually rest their finger on the trigger.

Some older bolt-action rifles designed in the 1940s through the 1970s aren't drop-safe because they weren't intended to be carried with the chamber loaded, but most modern designs incorporate better safety systems and are intended to be drop-safe with the safety engaged, and some incorporate passive safeties as well. Also, some older rifles and shotguns could be fired by closing the action, and the Remington 700 had a problem for a while in which a neglected and dirty rifle could fire when the safety was disengaged, but handguns designed to be carried loaded tended to have a lot more attention paid to those kinds of failure modes.

[Eleanors38]

18. In WW II, carrier personnel were warned to stay away from the propellers of fighters...

even when not running. The 18-cylinder engines would get extremely hot on sunny days at sea, and at least one cylinder was near TDC at any given time, and could fire off without electric ignition, thus spinning the prop. I've even seen an old Cushman 2-cycle scooter fire off in a parking lot. No one was around!