Accidental discharge
“An off-duty police officer went to an outpatient imaging center … to have an MR imaging examination. … The officer was carrying a model 1991 A-1 compact.45 caliber semiautomatic pistol …”
“… the officer apparently misunderstood and took the gun into the MR suite. …”
“Once the officer was inside the MR suite, the gun was pulled from his hand as he attempted to place the gun on top of a cabinet … The gun was immediately pulled into the bore, where it struck the left side and spontaneously discharged … The weapon’s thumb safety was reportedly engaged when the gun discharged.” …
“The gun likely discharged as a result of the effect of the magnetic field on the firing pin block. …” …
If only he’d had one of those plastic Glock 7s from Die Hard 2!
via KABA.
July 11th, 2008 at 9:14 am
OK. Argument time. I’m sure this debate is as bad as the Mac vs. PC, but at what point can a gun discharge without actually the user wanting it to and it be called ‘accidental’?
This seems like one of those events, although you could easily say the cop should have known better than to bring his weapon into the MR area and that by doing so, he was negligent.
July 11th, 2008 at 9:18 am
Barring totally unforeseen circumstances (like the cop did here) or firearm malfunction, they’re generally negligent.
July 11th, 2008 at 9:33 am
Standard rule is no metal of any kind in the MRI room.
July 11th, 2008 at 9:41 am
Pop quiz: what do you do with your carry piece when you go into a hospital to get an MRI?
a) Take it on in there!
b) Leave it with the MRI Tech.
c) Leave it in the car
…”I’m the only one in here qualified enuff”…
July 11th, 2008 at 10:02 am
IIRC, the same thing happened with a Glock not too many years back. There was a big thread about it back when I was still posting on GT in ’00 or ’01…
July 11th, 2008 at 10:04 am
…which should give an idea of how strong the magnets in those things are, since a Glock at rest doesn’t have a cocked striker.
July 11th, 2008 at 10:46 am
Damn! [Note to self: leave your Colt 1991-A1 Compact .45 in the car next time you go in for an MRI.]
Although, since I bought the pocket-sized Walther and the 5″ Springfield XD, I don’t carry the Colt anymore. Besides, it’s only a six-shooter.
July 11th, 2008 at 12:03 pm
sorry, but anyone in a MRI building can see the GIANT signs warning of no metal near it… that was negligent… now the gun going off was accidental in itself… but the person with the gun was negligent in his part…
July 11th, 2008 at 12:06 pm
*ponder*
If the primer’s stem was made of steel, could it have been shifted enough to light off the priming compund?
If that’s the case, *no* safety would have helped.
July 11th, 2008 at 12:07 pm
Side ponder;
Thanks to eddy currents, I wonder if an aluminum can, if placed in the field, could be yanked out fast enough to either rip it apart or melt it…
July 11th, 2008 at 12:13 pm
Interesting…
I’m wondering if it was something other than the firing pin striking the primer that fired the gun. The changing magnetic field would have created eddy currents in the metal. Those eddy currents would have heated all the metals. As soon as the primer reached high enough temperature it would have gone bang.
The question to ask is why all the cartridges didn’t go bang. If they shut down the MRI shortly after the first one went off then that could explain it. Another explanation could be that the metal of the chamber concentrated the magnetic fields. The rounds in the magazine didn’t have similar concentration.
July 11th, 2008 at 12:33 pm
I was going to say this seemed bogus to me. But then I read the radiologists incident report. The report is good reading – http://www.ajronline.org/cgi/content/full/178/5/1092. They conclude the firing pin block shifted due to the magnetic field and then the firing pin impacted the primer due to the pistol’s impact with the MRI machine.
PS – it seems this is an event from 2001 or earlier
Dr Strangelove – I not so sure an aluminum can would be affected by a magnetic field? The same doubts apply to stainless steel. The officer should of been carrying a stainless Colt…
July 11th, 2008 at 12:49 pm
I’ve been looking for that report for a year or so now! I read that a couple of years ago and then lost the URL.
For more MRI fun: http://www.simplyphysics.com/flying_objects.html and http://www.simplyphysics.com/burnsinthemagnet.html
July 11th, 2008 at 12:57 pm
“I not so sure an aluminum can would be affected by a magnetic field?”
Non-ferrous metals can get eddy currents; I used to work with them quite a bit. I’ve seen copper go cherry and aluminum slag down in magnetic environments within seconds.
July 11th, 2008 at 12:58 pm
Not all stainless steel is non-magnetic. I’m not certain about the alloys used for handguns.
July 11th, 2008 at 1:48 pm
Not all stainless steel is non-magnetic. I’m not certain about the alloys used for handguns.
At the field intensities of an MRI, just about anything with a substantial iron content can be considered magnetic. There’s some magnetism even in the non-mag stainless alloys, but you can’t really notice it at normal field intensities. At the 10k to 20k Gauss of an MRI machine? I’m not taking any bets on stainless not exhibiting magnetic behavior. That’s a whole bunch of field.
July 11th, 2008 at 1:54 pm
Eddy currents are created in any conductor in the presence of a changing magnetic field. As long as the conductor is not a superconductor there will be heating.
I’ll have to read the report when I have more time. If the gun fired on impact with the machine then the eddy current hypothesis should be thrown out.
July 11th, 2008 at 3:03 pm
the report isn’t entirely clear on just when the 1911 fired (it likely can’t be, as there was probably only one eyewitness, who would have had plenty of reason to be shook up by the incident) but implies that it occurred on impact.
annoyingly, the report doesn’t seem to mention if the primer was dimpled by the firing pin or not. that’s frustrating, since it does mention the casing was recovered.
July 11th, 2008 at 7:38 pm
First, I’m a Ph.D., not an MD. Second, I work with PET scanners, not MRIs. But I’ve taken a few courses in MRI physics in the past…
A friend of mine, when his GE Signa scanner (same model, as close as I can tell from the article) was being installed, tied a wrench to a string and attached it to the doorknob to the room. When the door swung in, it got close enough to pull the wrench toward the magnet, so it quickly ( < 1 sec ) was pointing straight at the magnet. A good visual clue. Closing the door got it _just_ far enough away to drop back down. He did that to remind the contractors who were doing finishing work that “we meant it, guys.”
However, people do dumb things. I’ve had folks tell of patients, where the elderly gentleman was on the bed being pushed into the scanner, when his wife asked, “That sign about no metal and no pacemakers… it doesn’t apply to _him_ does it?”
I’m not sure where I stand on this. I mean, the cop disobeyed big signs, on a misunderstood verbal OK. Yeah, and if a cop is at the corner directing traffic, he is the sign, not the traffic light. So in his mind a verbal OK overrides the sign. And granted, carring a 1911 locked&cocked is not unsafe; there’s not one but two safeties, then you still have to pull the trigger.
On the other hand, carrying with one in the pipe in a hospital environment seems pretty damned dumb. But I’m not sure how much of that is common sense and how much is just the respect for big magnets that can only come from experience.
July 12th, 2008 at 12:07 am
Taking a large metal object (like a wrench) close enough to an NMR’s magnet to cause it to move towards the magnet is certainly enough to mess up the shimming in my limited experience.
Those “no metal objects” rules are to protect the machines more than they are meant to protect the patients. Funny story, though; I’m glad no one was hurt.
July 14th, 2008 at 1:19 pm
So how would all of this come into play when using very strong (rare earth) magnets to store or hold handguns? Say under a table or behind a clothes dryer for example?
Should I be looking for safer ready-storage techniques over the use of these magnets or are they simply not strong enough to cause the type of discharge mentioned in this article?
So far I’ve had no problems at all, but if there’s even a remote possibility of an accidental discharge caused by the magnets themselves, I’ll be changing things ASAP.