Electromagnetic coil gun seized in Japan | Hacker News Reader

Electromagnetic coil gun seized in Japan

www3.nhk.or.jp

56 pointslando231983 comments

With a background in electronics, just looking at that gun, it seems very unlikely it would do more than give someone a bruise.

That appears to be a single coil which is chonky as hell, which means you need a high voltage to drive it. It looks like it also only has a single capacitor, the physical size of the which is too small to have enough energy to seriously drive a coil like that.

You can find videos on youtube of diy coil guns 5x the size that at best punch holes in 3mm particle board or one side of an aluminum can. There is no way that thing is actually going to kill someone.

So the suspect was arrested for possessing a coilgun, but it was only made illegal this June with the law taking effect in March next year? The timeline doesn't make any sense. Other news sources aren't helpful as they contain even less information.

Above all, how this was legal in Japan until very recently is beyond me. I thought Japan has strict gun controls in place.

Edit: Apparently coilguns are categorized as firearms, which is illegal today, if they're lethal enough.

https://newsdig.tbs.co.jp/articles/-/1563487?display=1

So this is mostly a funny thing for the news cycle and a major inconvenience for the suspect, and he will be released once they realize this thing isn't actually lethal?

A "good" way for authorities to show how they are on top of this and that you shouldn't share videos on coil guns on the internet. Seems a bit authoritarian.

No, he was arrested because it was deemed to be lethal.

There is no way this thing is actually lethal in any reasonable definition of "lethal firearm". Maybe if you bludgeon someone with it.

If you shoot with this thing from, let's say from 5 meters to the head, is there a decent risk of dying? If yes, it most definitely is lethal.

As much risk as throwing a rock from that distance, most likely. So no, probably not lethal.

I have personally got a small rock to the head and almost died.

It is about the accuracy and how fast can the other person react or protect themselves. I would say that guns like these exceed the throwing of rock with high numbers. You can also do it many times in a short duration.

Fireguns are effective for that particular reason. They are accurate, and there is no way to protect against, as they are very fast to use. And you are not limited to single throw.

He was over estimated the threat (Ed: or suggesting throwing it is more dangerous than firing it), the issue is capacitors suck.

A 95 MPH fastball which can seriously hurt has about 150J worth of energy. Meanwhile a professionally made coil gun using a lot more capacitors hit 10J and this isn’t nearly as powerful. https://en.wikipedia.org/wiki/GR-1_%22Anvil%22

Are slingshots illegal in Japan?

ChatGPT translation:

"Suspect Arrested for Possession of Electromagnetic Gun "Coilgun," Manufacturing Video Allegedly Published November 19, 2024, 1:40 PM

A 29-year-old suspect has been arrested on suspicion of violating Japan's Firearm and Sword Control Law for possessing a deadly electromagnetic gun, commonly referred to as a "coilgun." Reports indicate that the suspect also uploaded videos showing the manufacturing process to a video-sharing platform. The Tokyo Metropolitan Police Department is investigating the details.

The arrested individual has been identified as Nobuaki Usui (29), an unemployed resident of Nasu Town in Tochigi Prefecture.

According to the police, the suspect is accused of possessing a coilgun, a device that fires projectiles using magnetic force, at his home last month. The weapon falls under the suspicion of violating the Firearm and Sword Control Law.

Investigators discovered the videos during a "cyber patrol" and confiscated the content. Upon analysis, it was confirmed that the coilgun had a structure capable of firing live ammunition, making it a potentially lethal weapon.

The suspect reportedly stated during questioning, "I made it when I was in high school."

Regarding coilguns, a legal amendment was made in June of this year, and the possession of such devices will generally be prohibited by March next year. The police are currently conducting a free collection campaign, urging individuals to turn in coilguns at their nearest police station."

If the amendment hasn't come into effect yet, I wonder why he was arrested.

>The weapon falls under the suspicion of violating the Firearm and Sword Control Law.

> the possession of such devices will generally be prohibited by March next year. The police are currently conducting a free collection campaign, urging individuals to turn in coilguns at their nearest police station."

Reading the original Japanese article.

Police ceased the coil gun and determined that it was a potentially lethal weapon. The suspect was arrested under current law on this basis.

From March next year it will be illegal to posses coil guns at all (regardless of lethality).

Ahh, a machine translation issue. Okay, I'll go with that. Thanks!

If you look at the picture, it’s clearly a labour of love. I’m glad they don’t have this kind of dystopic thought police watching citizen videos where I live

That thing is clearly not a thought, but a literal lethal weapon. You know what would actually be dystopian? Gun violence happening on a regular basis.

Eh... That is not clear at all. Given typical coil gun efficiencies (single digit percentages), there is absolutely no way that this thing is even remotely comparable to a typical 9mm handgun (in projectile velocity and just general lethality).

Just ask yourself-- how many people are killed by coil guns each year? Stopping their proliferation strikes me as utterly useless regulatory overreach that benefits exactly no one, and deprives many a nerd of a cool hobby project.

It's built to imitate the _looks_ of a lethal weapon. Given its build quality and size I have my doubts that it can actually accelerate those bullets to a harmful speed unless you're staring down the barrel without eye protection. The most danger this appears to present to society is scare value and an unprotected fairly large capacitor, as a shock hazard to whoever is holding it.

There's a video of the suspect demonstrating its capability and it looks dangerous enough.

https://youtu.be/-Bm3278gk50?si=dmKK4qyTajAoACSi&t=30

It's putting tiny holes through thin cardboard at point blank. Sure it could probably injure your eye or something but it's not on the level of like a real handgun.

Of course, the headline just says it was 'seized'. That could happen for an airsoft gun in Japan for all I know.

It was ceased and the police determined it was a potentially lethal weapon on examination. The suspect was arrested on this basis.

Given the circumstances and confession I’m guessing this guy will be let off with a warning (deferred prosecution).

Police would never exaggerate their effectiveness to justify their behavior and funding. Never.

A sling is more dangerous than that thing.

Is that a cardboard box?

A child’s slingshot is more dangerous than this.

Don’t fall into the “scary weapon!” trope. Thankfully I live in America where most people don’t freak out like this and we can have cool hobby projects.

My index finger can also poke a hole in a cardboard box. This is a toy.

Just calling things "a labor of love" and suggesting if it is it shouldn't go against laws isn't really a good argument. I'm sure Ted Kaczynski was doing his actions out of a labor of love, he was just trying to make the world a better place (for his own definition of "better").

If criminals are openly talking about their crimes on the public facing internet, I'd hope the police would go after it.

It also looks like it would be pretty ineffectual. I suspect the amount of current needed to make it lethal ... would be a lethal current itself.

They are slowly getting better, but also much heavier. Here are a couple youtubers [1] hitting water balloons, watermelons, pineapples and soda cans. Demolition Ranch and Kentucky Ballistics

[1] - https://youtu.be/RkCNq9yICJ8?&t=391 [video][16 mins, but I skipped to 6m in]

Seems like a (modern) slingshot is a good deal more lethal than these.

It looks awesome to be honest and is probably part of the reason it scared the authorities. Had it looked more like a miniature potato cannon, I'm not sure they would've thought it any more dangerous than a slingshot.

Kind of reminds me how California's assault weapon ban seems to be quite centered around how "scary" the firearm looks, and not the capabilities of the weapon.

Codified into law there can be some reason to it. A butterfly knife isn't a lot more lethal than a similarly sized Leatherman. But a self-respecting gangster is going to go with the much cooler butterfly knife, which for many countries is enough reason to ban one but not the other.

However this should be a matter of law, not enforcement decisions.

I agree that may be a reason politicians ban weapons in similar laws, but I believe that is a really stupid reason.

In this situation, it does appear to me that the law insufficiently specifies what is legal, and it is unfortunate that this came down to an enforcement decision.

EMG-01 owner here https://arcflashlabs.com/

There's no way this homemade coilgun has the muzzle velocity to do anything but harm squirrels and similar. This is way overblown.

I imagine this (new) law has something to do with Shinzo Abe, who was assassinated with a homemade gun.

I think the primary benefit of an electromagnetic coil gun in an environment like Japan would be the capability to build one using off the shelf and unmonitored equipment. In the US it would be much easier to generate 3d printed guns, because finding ammunition with gunpowder inside is much easier.

The translation of the article is a little rough. It looks like maybe it was used as a curiosity instead of a tool for violence. I suspect actual criminals get along just fine with melee weapons and the occasional smuggled firearm.

This whole thing is cool in that it feels very much like a 21st century style crime. It's scary because I imagine disassembly would be an effective method of disposing of the murder weapon. In most jurisdictions it's possible to get a conviction without a murder weapon but requires more supporting evidence.

I find it very hard to believe it's anything more than a toy especially given the small size.

You would be surprised. I have seen coil guys about this size do significant damage to thin wood boards or cardboard.

Sure, it’s not going to do massive damage like a 7.62x51, but it’s still enough to seriously injure.

I think the larger question is proliferation and intent within a culture. For example, I’m of the opinion knives are a tool, but they can easily be used as a weapon. There’s a huge grey area between hobbies, tools, and weapons. I think it’s up to the collective groups to decide what’s appropriate.

I’m just curious with the downvotes to better myself - where was I off base?

An increasing number of HN users are now lazily downvoting things they disagree with, simply because they can't be arsed composing a coherent rebuttle. This leads to unpopular ideas being buried, groupthink and a lack of intelligent discourse.....

....And yes, this IS leading to this place becoming more and more Reddit like (no, that isn't a tired cliché, no matter what the FAQs claim).

Downvoting should be reserved for comments that detract from the conversation. Perhaps meta-moderation is needed to ensure this happens.

I appreciate the input. I recognize that I had brought up some issues that are polarizing (the article itself was a hot topic).

I personally put a lot of thought into and struggle with gun/weapon legislation. I very much enjoy hearing from others, and it has helped shape my opinion in this area over the years.

You do bring up a good point. I can’t help but wonder if there’s a better metric for comment “rank” rather than a binary up/downvote.

I have no idea why, it was good reply

I agree with that statement for this specific model. Maybe it's enough for lethal force, but probably less lethal than a kitchen knife. However larger and more powerful versions are possible. I think the lawmakers are correct in classifying this as a firearm, but perhaps the law should identify a minimum force threshold before it is classified as a weapon.

>I think the primary benefit of an electromagnetic coil gun in an environment like Japan would be the capability to build one using off the shelf and unmonitored equipment. In the US it would be much easier to generate 3d printed guns, because finding ammunition with gunpowder inside is much easier.

Why 3d printed guns? A CNC machine is also "off the shelf and unmonitored equipment", and would make a better gun than a 3d printed plastic gun that'll probably explode on you with one shot.

The main point is that limited access to ammunition would encourage innovation in generating force to propel the projectile in a way that isn't true in North America.

What happens if it's not a rounded bullet but a pointed dart at the same speed?

Is there a reason firearm manufacturer's aren't pursuing the creation / sale of 'coil guns' as actual products? I get that you're introducing reliance on a battery, but you're also gaining (I assume) near silent operation. And most incidents involving a firearm don't extend past one or two magazines anyways.

Seems to me like a cleaner, more "futuristic" weapon. The "hobby" version of this weapon photographed in the article already looks quite clean.

They’re very underpowered compared to an actual gun.

What if it were a rifle to house a much larger electromagnet?

There is a company messing around with commercial coilguns: https://arcflashlabs.com/product/emg-02/

They basically make something in a rifle form factor. It's still limited to 75m/s. That's low end air rifle speed.

The problem is that their efficiency at converting electricity into projectile kinetic energy is really bad (like single digit percentages bad), getting electrical energy and power density is quite difficult in the first place (capacitors have abysmally bad energy density compared to gunpowder), and coils absolutely hate having their current changed quickly (which you need for this to work).

Great and informative response, thank you

The problem with coil guns in particular is the ferrous slug is drawn to the center of the magnetic field. The field has to be collapsed at the right time to avoid sapping velocity from the slug, counterproductively.

Many designs that achieve respectable velocities use a multi-stage coil, which requires precise timing for each magnetic field, a lot of power, and high current capability. Generally, that means large batteries for a power source and large capacitors to feed the coils, which becomes heavy and expensive.

Even rifle variants rarely make more energy than a .22 LR, a feat which is easily overshadowed by air guns several hundred years old.

https://en.m.wikipedia.org/wiki/Girardoni_air_rifle

> his air gun which fired 22 times at one charge

I think these might be classifiable as assault weapons.

If anything, I think it goes to show that weapons like this are anything but novel and unusual.

Conventional guns are also more powerful as rifles than handguns, the same problem remains.

The electromagnet isn't the issue, it's the capacitors to power the magnets. A coil gun capable of matching a small handgun would be too heavy to reasonably carry. At the scale where they could become competitive with a conventional gun, you have an artillery piece.

An artillery shell that only required slugs without more complex manufacturing would be pretty useful…

The energy density and expense of capacitors, along with the efficiency of the electromagnetic coils makes them impractical.

Coil/rail guns that achieve velocities comparable to real firearms are actually quite loud, as the air is compressed and superheated in front of the projectile, which creates a report at the muzzle. However, most man portable variants are limited to around the energy of a .22 LR. Even air guns are more powerful and practical.

As an example of a weapon that's practical yet not portable, take a look at the Navy's 155mm rail gun. https://youtu.be/O2QqOvFMG_A

"Silent" is going to be relative. Yes there's no pop of the propellant, but you've still got to accelerate an interesting mass to interesting speeds in a very short barrel. That's going to make a noise in its own right just from the mass reaction.

I think there's at least one commercial maker (if still in business anyway), but they aren't anywhere near as accurate or powerful as traditional chemically powered guns while being a lot heavier, so more of a novelty than anything.

Firearms need to be practical and reliable first (you only expect to use them in a worst case scenario), the technology required to make a coilgun lethal is neither practical nor reliable, and its more complex to operate and maintain.

It’s the same reason why we don’t use coilguns anywhere else, why fix what isn’t broken?

> you only expect to use them in a worst case scenario

I'd hardly call ordinary sporting or pest control as "worst case scenario". Indeed, your comment betrays your nationality!

That's interesting, I wonder if you could have a hybrid weapon that uses the first stage gas from gunpowder like a normal gun, but uses the rest to drive a cylinder that rakes a magnet down a coiled cylinder to supply the jolt to boost the projectile using EM force?

The advantage would be better efficiency, similar to how hybrids are more efficient than ICE, which are only 35% efficient on a good day.

Hybrids and trains don't get their efficience from the conversion. They both lose a lot in the conversion itself.

They get their efficiency from smoothing out upscs & downs and letting the power source run more steadily and spend more time in it's own sweet spot. IE the ice engine is less efficient when changing and when running at any rpm other than the peak of it's curve. The battery lets the the ice run steady at it's one best rpm and the battery does all the stop & go.

There is very very little opportunity for "flattening out peaks & valleys" in a single pulse, and no chance at all to do it enough times to regain so much energy that way that it more than pays for the conversion loss.

And in any event, coils are just super super fundamentally inefficient at bursts. The term is literally called impedance, because it litetally impedes energy flow. It's similar to resistance and is even measured in ohms. It's like a spring. You put the energy in and it doesn't immediately come back out, it eventually comes back out, slower and a bit less of it than went in. Converted to mechanical energy instead of picked up by another coil or bounced right back out the same wires where it went in and you you almost none of the energy back out.

There are people trying. See, for example, Forgotten Firearms' review of the ArcFlash Labs EMG-02 CoilGun: https://www.youtube.com/watch?v=EwHRjgVWFno

Not particularly powerful and it's unclear that any amount of engineering can make it deliver more power to each round while still keeping it man-portable.

"accused of possessing a coilgun, a device that fires projectiles using magnetic force"

"Upon analysis, it was confirmed that the coilgun had a structure capable of firing live ammunition"

One of these is not like the other.

Does this seem lethal to you? If that's a big aluminum electrolytic capacitor at the bottom, and those have energy densities around 1-3 J/cm3, then I'd estimate it could hold at most 50-200J. A fired .22 bullet can have an energy around that, so plausible? Efficiencies aren't going to be that good though, so maybe not. Any better estimations?

Good grief every house has dozens of solenoids in various appliances that deliver the same punch as that thing. They can all poke a hole through cardboard, and so can a baby with a pencil.

“The killing power is the electromagnetic gun, the gun is held by the gun, the gun is held by the gun, and the 29-year-old blunderbuss is used to tolerate the suspect. The Suspicious Person is produced and written by the anime and distributed by the anime and distributed by the public.”

Yeah, we have a long way to go with translations.

I've noticed everything except like... english <-> spanish and english <-> french is absolute dogshit.

how many other languages do you know

I'm from the US dude I don't even know spanish or french lol

For many languages, the translation matrix doesn't work well directly, so you end up with Japanese -> English -> Spanish when you select Japanese -> Spanish. You lose details at every step, but the end result is still better than the rather unreliable direct translation.

Translations are also a lot better when the languages share more grammar and cultural history. Japanese has grammatical constructs that simply do not exist in English (and vice versa), so providing accurate mapping is an impossible task.

English <-> (insert Germanic or Romance language here) is always pretty solid, but should that be a surprise? This is also the case that is easiest for people.

I wonder if anyone has played around with Language A <-> Common Intermediate Representation <-> Language B. If not, I nominate Lojban for the CIR.

The built-in translation feature in Google Chrome translated it pretty much perfectly idiomatically for me

It seems that Google Translate assumes Chinese as the source language, instead of Japanese.

Just change the detected source language to Japanese and it will translate a lot better - for some reason it defaults to Chinese as the source language. The person above has posted a wrong translate URL

https://translate.kagi.com/https://www3.nhk.or.jp/news/html/...

Do we?

https://www3-nhk-or-jp.translate.goog/news/html/20241119/k10...

Edit: correct link! Thanks child

That translate from Taiwanese Mandarin[0] (note the _x_tr_sl=zh-TW)

The correct link would be https://www3-nhk-or-jp.translate.goog/news/html/20241119/k10...

[0]: Presumably "Chinese (Traditional)" in the selector, but it shows that it is translating from "Chinese (Simplified)" until you click the drop down at which point it shows "Chinese (Traditional)" as selected in the selector box: https://i.imgur.com/kjZ1WQk.png

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