# Guns and magnets **URL:** \ **Category:** Factual Questions\ **Created:** [February 10, 2006, 12:05am UTC](https://boards.straightdope.com/t/guns-and-magnets/343770 "2006-02-10T00:05:08Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Loach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/loach/32/350_2.png) [@Loach](https://boards.straightdope.com/u/Loach)\ **Post date:** [February 10, 2006, 12:05am UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/1 "2006-02-10T00:05:08Z")
I am a police officer and at work we recently were told of a potential problem. It came down to us through official channels from the state. When I heard it it seemed like an Urban Legend and I wasn’t the only one who thought so. The email stated that in some police department officers entered a doctors office that contained a MRI. Somehow the MRI magnetized their guns and rendered them inoperable without them knowing it. It sounded like BS to me. I couldn’t find anything about it on Snopes. I am not an expert on the manufacture of guns but from what I do know it seems unlikely. We have Glocks. The lower receiver is plastic so interference with the slide is not an issue. Can the firing pin be magnetized so it won’t move? Can the slide become so magnetized by a MRI that it won’t move? Would it become magnetized at all? I would love to be able to post a cite on our bulletin board with the truth about this. Please try to keep the “I don’t think so” posts to a minimum, thats were I am now. Facts please (unless your post is otherwise interesting, then fire away). ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [February 10, 2006, 12:13am UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/2 "2006-02-10T00:13:04Z")
Apparently, it [actually happened](http://www.afte.org/announcements/offsafetymri.htm), on at least one occassion. In this case: > [@](#): > > In July 2001, an officer from the Manheim Township (Lancaster County, Pennsylvania) Police Department had an incident where his issue firearm malfunctioned. The Smith & Wesson, Model 4013, .40 S&W caliber, semi-automatic pistol was found to have a magnetized firing pin, which stuck to the side of the channel within the slide. Upon inspection, it was determined that the entire pistol had become so magnetized that paper clips actually stuck to any metal surface. The department armorer was able to demagnetize the firearm with the use of a high-power, videotape-erasing unit after complete disassembly. > > When the malfunction was discovered, the officer had no idea of when or how his pistol had become magnetized. A review of the officer’s activities, revealed that he had investigated a burglar alarm call at a medical office that was equipped with a Magnetic Resonance Imaging (MRI) unit. During the investigation, the officer had walked into the MRI suite that magnetized the pistol. MRI medical personnel have detailed instructions on safety, which include keeping metal objects away from the unit. Upon further inspection, two additional officer’s firearms were also found to have been magnetized. Degaussing would be simple enough, since the sort of steels used are fairly low coercivity–that is, it doesn’t take a very strong field to magnetize or demagnetize them. In the above case, a videotape degausser was used, but a TV/monitor degaussing coil would also work quite well. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [February 10, 2006, 12:23am UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/3 "2006-02-10T00:23:26Z")
Beaten on preview, but there is also [this incident](http://www.cbsnews.com/stories/2001/07/31/national/main304167.shtml) > [@](#): > > In Rochester, N.Y., last year, an MRI magnet yanked a .45-caliber gun out of the hand of a police officer, and the gun shot a round that lodged in a wall. An [MRI site (also from Rochester)](http://www.cis.rit.edu/htbooks/mri/chap-9/chap-9.htm) makes an additional comment: > [@](#): > > Another frightening story was of a law enforcement officer being allowed to go near a magnet with a loaded firearm. The handgun was pulled out of its holster, and into the magnet. The force of the impact with the magnet caused the gun to discharge. Luckily, no one was injured in this incident. In addition to the damage to the MRI and the bullet lodged in the scan room wall, the gun was magnetized. Mechanical objects, in general, do not function properly when magnetized. Please, respect the physical laws of nature that cause ferromagnetic objects to be attracted by magnets! ---
**Author:** ![danceswithcats](https://avatars.discourse-cdn.com/v4/letter/d/9e8a1a/32.png) [@danceswithcats](https://boards.straightdope.com/u/danceswithcats)\ **Post date:** [February 10, 2006, 1:03am UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/4 "2006-02-10T01:03:45Z")
My skepti-sense is tingling on the latter “cites”. Think about it-if the magnetic pull were sufficient to take the weapon out of the officer’s grasp, what became of the other metallic objects on his person? Ballpoint pen, uniform and personal jewelry, baton lazy ring, belt buckle, spare clip(s), portable radio, flashlight, etc. Uniformed officers drag a lot of stuff around, and from the sound of those quotes, an MRI would pull him across the room. No offense meant **Exapno Mapcase** , but I’m feeling :dubious: ---
**Author:** ![ryobserver](https://avatars.discourse-cdn.com/v4/letter/r/b2d939/32.png) [@ryobserver](https://boards.straightdope.com/u/ryobserver)\ **Post date:** [February 10, 2006, 1:36am UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/5 "2006-02-10T01:36:27Z")
> [@danceswithcats](#): > > My skepti-sense is tingling on the latter “cites”. Think about it-if the magnetic pull were sufficient to take the weapon out of the officer’s grasp, what became of the other metallic objects on his person? Ballpoint pen, uniform and personal jewelry, baton lazy ring, belt buckle, spare clip(s), portable radio, flashlight, etc. Uniformed officers drag a lot of stuff around, and from the sound of those quotes, an MRI would pull him across the room. No offense meant **Exapno Mapcase** , but I’m feeling :dubious: Well, first, not all metal items are attracted by magnets. MagLite flashlights have aluminum cases; ammunition is brass and lead; none of these metals are attracted to magnets. Jewelery that’s attracted by magnets would have to be really cheap stuff. Second, not all the items you mention would necessarily be metal. Most ballpoint pens are plastic nowadays. Third, even if 20 metal items on your person are pulled into an MRI, if one of them is a gun, you’re going to be a damn sight more worried about the one gun than the 19 other items, and they may not make it into your report on the matter. I’m not skeptical about this report, as you can guess. I’ve known people who worked with research MRIs, and read case reports of what can happen with the medical ones. I’ve heard of a janitor taking a floor buffer into an MRI room and seeing it fly across the room and slam into the machine hard enough to dent it badly. I’ve read of a patient hit in the head by an infusion pump that flew off the gurney into the MRI machine. Incidents of the latter sort are common enough that MRI-compatible pumps and other machinery have been designed since the machines became popular. Those magnets are ferocious. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [February 10, 2006, 1:42am UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/6 "2006-02-10T01:42:19Z")
People have been pulled off their feet and into the “donut hole” in an MRI by the magnetics acting on items they are wearing. One of the nastiest cases I heard about was a firefighter who’s air bottle got “grabbed” by an MRI and both it and he were pulled into the machine. He was so doubled over and compressed by being jammed in there that there was concern he’d suffocate. They eventually had to turn off the machine, demagnitize it, and partially disassemble it to get him out. The man suffered back and torso injuries as a result. MRIs can be quite dangerous. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [February 10, 2006, 3:32am UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/7 "2006-02-10T03:32:36Z")
> [@danceswithcats](#): > > My skepti-sense is tingling on the latter “cites”. Think about it-if the magnetic pull were sufficient to take the weapon out of the officer’s grasp, what became of the other metallic objects on his person? Ballpoint pen, uniform and personal jewelry, baton lazy ring, belt buckle, spare clip(s), portable radio, flashlight, etc. Uniformed officers drag a lot of stuff around, and from the sound of those quotes, an MRI would pull him across the room. No offense meant **Exapno Mapcase** , but I’m feeling :dubious: Here are the original stories from the Rochester Democrat & Chronicle, although the full stories are blocked behind a payment wall. > [@](#): > > 1. DAILY DIGEST > September 15, 2000 •• 406 words •• ID: roc2000091510092197 > Test too risky for magnet-pulled gun It would be too risky to test the gun yanked out of an off-duty city police officer’s hand by a heavy-duty magnet this week, a firearms expert said yesterday. The magnet, used for magnetic resonance imaging tests, might have changed the molecular structure of the .45-caliber handgun, said Sgt. William Benwitz, who runs the firearms training unit at the Scottsville Road training academy. "Until we send this gun back to the > > 2. DAILY DIGEST > September 14, 2000 •• 347 words •• ID: roc2000091410192034 > MRI `disarms’ police officer Just call it a really magnetic attraction. An off-duty Rochester police officer went to Borg Imaging at 200 White Spruce Blvd., Brighton, yesterday for a magnetic resonance imaging test. The officer asked an office worker about his handgun and, according to Brighton police, was told to keep it with him. But as soon as the officer entered the room holding MRI equipment, the heavy-duty magnet yanked the gun from his hand. Even the bullets Seems legit to me. ---
**Author:** ![Jayrot](https://avatars.discourse-cdn.com/v4/letter/j/3ec8ea/32.png) [@Jayrot](https://boards.straightdope.com/u/Jayrot)\ **Post date:** [February 10, 2006, 3:43am UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/8 "2006-02-10T03:43:20Z")
> [@danceswithcats](#): > > My skepti-sense is tingling on the latter “cites”. Think about it-if the magnetic pull were sufficient to take the weapon out of the officer’s grasp, what became of the other metallic objects on his person? Ballpoint pen, uniform and personal jewelry, baton lazy ring, belt buckle, spare clip(s), portable radio, flashlight, etc. Uniformed officers drag a lot of stuff around, and from the sound of those quotes, an MRI would pull him across the room. No offense meant **Exapno Mapcase** , but I’m feeling :dubious: Observe: [DANGER! Flying Objects!](http://www.simplyphysics.com/flying_objects.html) ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [February 10, 2006, 3:58am UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/9 "2006-02-10T03:58:05Z")
> [@Jayrot](#): > > Observe: [DANGER! Flying Objects!](http://www.simplyphysics.com/flying_objects.html) Wow! I didn’t know tigers were magnetic! 😉 I had to setup some computer systems around an MRI lab once and needless to say the presence of such a magnet had us all a bit concerned (not that we thought we’d be close enough to have the machines fly across the room but that the field would be strong enough to wreak havoc on the computers). I do not know if all hospitals do this but in our case they had a map (looked kind of like a topographical map) that showed the magnetic strength at various distances from the machine. One line was marked as the point of no return for your credit cards (which they actually marked on the floor with a painted line). ---
**Author:** ![danceswithcats](https://avatars.discourse-cdn.com/v4/letter/d/9e8a1a/32.png) [@danceswithcats](https://boards.straightdope.com/u/danceswithcats)\ **Post date:** [February 10, 2006, 4:16am UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/10 "2006-02-10T04:16:25Z")
Thank you for further info, all. ---
**Author:** ![krisolov](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/krisolov/32/3724_2.png) [@krisolov](https://boards.straightdope.com/u/krisolov)\ **Post date:** [February 10, 2006, 1:21pm UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/11 "2006-02-10T13:21:14Z")
Having worked for a company tha serviced these magnets by supplying them with liquid helium, I can say that these sorts of events do happen from time to time. Oxygen tanks needed for patients in an MRI need to be aluminum, not the ordinary steel E cylinders. Occasionally a mistake is made, resulting in a steel oxygen tank being pulled into the magnet, often causing significant damage to the unit. ---
**Author:** ![Loach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/loach/32/350_2.png) [@Loach](https://boards.straightdope.com/u/Loach)\ **Post date:** [February 10, 2006, 1:23pm UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/12 "2006-02-10T13:23:54Z")
Thanks for the cites. The only thing that rings false with me is the report of the gun being yanked out of the holster. Weapons retention holsters are the norm. There is usually a manual release or two that need to be manipulated in order to get the gun out of the holster. I could see it being pulled out of someones hand but not the holster. ---
**Author:** ![Mindfield](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mindfield/32/19759_2.png) [@Mindfield](https://boards.straightdope.com/u/Mindfield)\ **Post date:** [February 10, 2006, 1:47pm UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/13 "2006-02-10T13:47:45Z")
Funny, but this exact phenomenon was a plot point in a recent CSI episode. It seemed a little far-fetched to me, but my knowledge of MRIs is limited to what they do and a bit of how they do it, so I didn’t know enough to determine the effects of just walking by one in operation. I didn’t realize the magnetic field on those things was that strong – but the I guess given their size, there’s a reason the examiners are sheilded in another room during the process. ---
**Author:** ![AskNott](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/asknott/32/5790_2.png) [@AskNott](https://boards.straightdope.com/u/AskNott)\ **Post date:** [February 10, 2006, 7:11pm UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/14 "2006-02-10T19:11:55Z")
My brother repairs MRIs, and he’s told me some stories. Even some things that contain no iron are affected. He showed me an aluminum sign, then he stood it upright inside the magnet. When he let go, it very slowly fell to horizontal. He said, even though he knew better, he has forgotten and killed a few watches and credit cards. ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [February 10, 2006, 8:16pm UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/15 "2006-02-10T20:16:10Z")
> [@AskNott](#): > > My brother repairs MRIs, and he’s told me some stories. Even some things that contain no iron are affected. He showed me an aluminum sign, then he stood it upright inside the magnet. When he let go, it very slowly fell to horizontal. > > . This is due to the motion inducing eddy currents in the conductive metal that in turn generate fields that oppose the motion. It’s called magnetic damping. If you take a small cylindrical rare-earth magnet, and drop it through a copper tube, the effect will be very obvious. In the case of the gun being pulled from the holster, it is not inconcievable that the officer had his hand on the gun, and deactivated the retention device, as the cite stated he was investigating a burgaler alarm. I have certainly observed this in routine traffic stops…gun not drawn, but hand on gun with thumb strap unsnapped. At one company where I worked, a couple of cow-orkers had “liberated” one of those St.Pauly Girl life-sized cutouts you see in bars and it became the department mascot. One night somebody left the front door unlocked, the wind set of the alarm, and cops showed up. The next day one came by and suggested that we either be more careful about locking up or get rid of “that F’ing girl”, as it had scared the hell out of him, and he said he definatly did draw on it. ---
**Author:** ![Loach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/loach/32/350_2.png) [@Loach](https://boards.straightdope.com/u/Loach)\ **Post date:** [February 10, 2006, 10:22pm UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/16 "2006-02-10T22:22:51Z")
> [@Kevbo](#): > > This is due to the motion inducing eddy currents in the conductive metal that in turn generate fields that oppose the motion. It’s called magnetic damping. If you take a small cylindrical rare-earth magnet, and drop it through a copper tube, the effect will be very obvious. > In the case of the gun being pulled from the holster, it is not inconcievable that the officer had his hand on the gun, and deactivated the retention device, as the cite stated he was investigating a burgaler alarm. I have certainly observed this in routine traffic stops…gun not drawn, but hand on gun with thumb strap unsnapped. > > At one company where I worked, a couple of cow-orkers had “liberated” one of those St.Pauly Girl life-sized cutouts you see in bars and it became the department mascot. One night somebody left the front door unlocked, the wind set of the alarm, and cops showed up. The next day one came by and suggested that we either be more careful about locking up or get rid of “that F’ing girl”, as it had scared the hell out of him, and he said he definatly did draw on it. Although you can still get holsters with just a strap that is not what I mean by a weapons retention holster. Though it is not impossible for a police officer to have such a simple holster it is not likely. I’ve had holsters that you have to push back and out on the gun while releasing the strap at the same time. I have had holsters that you had to push down and forward on the strap while pushing down on a button on the side before removing the gun. It’s supposed to keep someone else from removing it while you are rolling around on the ground with them. It should keep a MRI from doing the same. ---
**Author:** ![Fish](https://avatars.discourse-cdn.com/v4/letter/f/bc8723/32.png) [@Fish](https://boards.straightdope.com/u/Fish)\ **Post date:** [February 11, 2006, 12:17am UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/17 "2006-02-11T00:17:35Z")
> [@krisolov](#): > > Oxygen tanks needed for patients in an MRI need to be aluminum, not the ordinary steel E cylinders. Occasionally a mistake is made, resulting in a steel oxygen tank being pulled into the magnet, often causing significant damage to the unit. Just here to say that yes, I work in a radiology clinic with an MRI, and my administrator told me it _will_ pull steel oxygen tanks across the room. We have a sign up prohibiting them, but ambulance crews don’t always remember. Our MRI has been damaged twice as a result of steel oxy tanks. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [February 11, 2006, 12:25am UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/18 "2006-02-11T00:25:28Z")
I wonder why MRI rooms don’t have ferromagnetic metal detectors at the entrance? Seems like this kind of thing happens with surprising regularity, and given that an MRI machine costs more than my house it seems only prudent to have minimal technology in place to prevent this kind of accident. ---
**Author:** ![krisolov](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/krisolov/32/3724_2.png) [@krisolov](https://boards.straightdope.com/u/krisolov)\ **Post date:** [February 11, 2006, 1:02am UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/19 "2006-02-11T01:02:54Z")
> [@Q.E.D.](#): > > I wonder why MRI rooms don’t have ferromagnetic metal detectors at the entrance? Seems like this kind of thing happens with surprising regularity, and given that an MRI machine costs more than my house it seems only prudent to have minimal technology in place to prevent this kind of accident. And I wonder how those detectors would be influenced by the MRI. I suppose you could put it far enough away, but that might take up a largish amount of space around the magnetized area. Probably not always practical. ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [February 11, 2006, 2:26am UTC](https://boards.straightdope.com/t/guns-and-magnets/343770/20 "2006-02-11T02:26:23Z")
> [@Loach](#): > > Facts please (unless your post is otherwise interesting, then fire away). Most areas where an MRI is located are posted to prohibit bringing any metallic object into the proximity of the MRI machine. It uses a very intense magnetic field (don’t recall the intensity) which could rip the gun out of it’s holster or your hand, make lethal projectiles out of O2 tanks, and other assorted disasters. It could possibly magnetize gun components to make it’s operation erratic or to malfunction. IOW Beware of the MRI! [Next page](https://boards.straightdope.com/t/guns-and-magnets/343770.md?page=2)