Is it mechanically possible for a Sig Sauer P320 to discharge without the trigger being pulled?

john.k said:

As Sir Charles Ross of Ross Rifle fame said.....No gun is foolproof ,therefore fools should not have them.

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......Some fools found out with one of Sir Charlie's bolts stuck in thier heads.

I believe thats why he made the statement.

QT: (Approach it properly and accurately; leave the fairytale nonsense for the holidays.)
There is nothing fairytale about telling kids to never point a gun at anything you don't want to be shot.
I have been shooting since about 10 years old ..and had a gun just go off unexpectedly once, lucky I did not put a hole in my ear.

Kids in Michigan are Deer hunting at 10 years old.

Teaching gun use at a Pheasants Forever event and asking each kid coming up to shooting to tell me a gun safety rule one kid who was about 5 or 6 said "Don't shoot the teacher".

A buddy had a Savage 30/30 don't remember the model but looked like a Winchester 94. I thought it was a pretty neat gun until one time when I was pulling the leaver back with my trigger finger outside the guard it went off just as the breech was closing. Lucky the resulting fire ball didn't blind me as I watched magazine spring fly off and I had the gun in two pieces . Buddy says it does that sometimes! No shit.

All guns are loaded and don't point a gun at something you don't want to shoot.

There is a coroners case here right now about a guy shot with a cheap single hammergun.........seems quite likely he was pulling the gun out of a pickup by the muzzle...........the family insist he was murdered .....but there have been countless accidents taking guns out of vehicles.

Whenever there is an accidental discharge, there is a very strong desire on the part of the handler to blame the firearm or someone else. (See Alec Baldwin.) I have experience in these matters as an Expert Witness in Federal Court.

Teaching gun use at a Pheasants Forever event and asking each kid coming up to shooting to tell me a gun safety rule one kid who was about 5 or 6 said "Don't shoot the teacher".

Oh. that reminds me ..Good to think about swing-around considerations when teaching newbies, couple if poles sticking up off the bench or a chord on the barrel, people can move pretty fast just when your look away.

"Good to think about swing-around considerations when teaching newbies..."

I've got a nice single-shot 22 for that. Remington 41, I think. Cuts down on the worry factor.

jim rozen said:

"Good to think about swing-around considerations when teaching newbies..."

I've got a nice single-shot 22 for that. Remington 41, I think. Cuts down on the worry factor.

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A buddy of mine used to work the range at a summer camp, youngest age allowed to shoot was 8. It was still plenty terrifying for him when a punk kid grabbed his .22 and swung it around to face him, saying "hey, the trigger's broke" while operating the (actually functional*) trigger to prove his point. The kid's section of the range had cables attached to the front of the stocks so they could not be pulled out of the shooting frames during shooting hours following that incident.

*Turned out to be a simple misfire. If it had been a hangfire or something else, things could have been much worse.

One does not understand gun safety until you get slapped down hard and embarrassed in front of many others.
Dad did this to me big time. This hurt so bad but I will never forget that lesson.
Bob

john.k said:

There is a coroners case here right now about a guy shot with a cheap single hammergun.........seems quite likely he was pulling the gun out of a pickup by the muzzle...........the family insist he was murdered .....but there have been countless accidents taking guns out of vehicles.

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Had a relative in Canada killed that way. He was out hunting and didn't unload the gun before crossing a fence. After he crossed he apparently reached over to pull the gun up and the trigger must have snagged.

years ago there was a utube vid of a guy banging a auto shotgun down on the ground.....it goes off ,and you can see the charge removing one layer of skin off his forehead ............a very lucky guy.

The discussions I have been following are citing "sear creep" as a potential explanation.
I hear but have not seen the videos where a holstered firearm does fire with no hands anywhere nearby during a range session.

The P320 and the HK9 series as these have the striker fully cocked by the action.
The trigger lets off the striker as much as letting a hammer fall- one a linear action the other rotation.
Not anything stopping a bit of a sear problem to make these let off when you don't want them to..

jscpm said:

I notice that Sig Sauer, a manufacturer located near me, is getting sued because people are saying their P320 handgun has a tendency to fire spontaneously--without the trigger being pulled.

I am not familiar with the firing mechanism used in such guns, so I am wondering if, from a mechical point of view, it is physically even possible for the gun to discharge without the trigger being pulled.

I know this is more of an engineering question than machining, but I suspect there are some machinists here that might have some pretty detailed knowledge of the innards of these contraptions, maybe a better knowledge than the engineers in some respects.

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The short answer is yes.

The longer answer is: (as a previous poster pointed out) the 320 "cocks" the striker back when the slide moves to the rear, and then the sear retains the striker under almost* full spring tension (*the trigger mechanism pushes the striker very slightly back before the sear releases). Sig reworked the sear mechanism awhile back to make this less likely (when they were having issues with them drop firing), so it "shouldn't" happen. My suspicion (based on the details in the complaint) is that this may be a wear and/or maintenance issue.

It seems to only be happening to:
-the models with no external safeties (the ones the military uses have these safeties, which may be why they haven't experienced this issue (that I know of))
-issued to smaller departments (who are unlikely to have armorers on staff or regular maintenance and inspection intervals)
-after longish hard lives, probably with multiple officers being issued the same weapon over it's service life
-this may explain why this issue isn't happening to many (if any) civilian users, and all the anecdotal claims of "this never happens to me". Their weapons are simply better maintained and/or less abused.

That said, a fair number of cases are likely ND rather than AD, but reported as AD for insurance/discipline purposes. But some of them may be AD. We'll have to wait for further engineering analysis of the effected pistols before we know anything with any degree of certainty. I sold mine some years back, or I'd have done a deeper look at the mechanism to see exactly where/how they could wear and result in this problem.


Note that when I say abused, I don't mean "fired a high number of times". I mean cycled/shot/dry fired, with grit/dust/carbon in the trigger mechanism, polishing/grinding the mating surfaces out of spec.
I was shooting with an LEO buddy one time when his Glock 19 suffered from a dead trigger (wouldn't reset). He asked me to take a look. When we took the slide off, the trigger pack was caked with junk. Lint, dust, sand, powder fowling, etc. Looked like he had been storing it in his shop apron for a year or two (it was his duty weapon). He had literally never cleaned it in the 3 years he'd been carrying/shooting it, and had no idea if it was cleaned before it was issued to him. Most LEO aren't "gun guys", even the ones who shoot more often than the min. qualification requirements. I'm not one of those "clean it after every range trip" guys, but my carry piece gets field stripped and blown out with a compressor every 3-6 months. The amount of crap that gets into the action just from life is surprising.

The short answer is yes, very unlikely is a 98 Mauser with the safety fully on likely to go off but even that should not be trusted.
People get killed by parked cars

Never work under a car up on cinder blocks.... Ends badly.

Seems the army here is buying SIG P320 handguns.