[ZFleck]

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.

[jakogut]

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

[regularfry]

"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.

[overstay8930]

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?

[GJim]

> 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!

[ThrowawayR2]

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.

[gosub100]

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.

[Brian_K_White]

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.

[techbro92]

They’re very underpowered compared to an actual gun.

[kingkawn]

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

[myrmidon]

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).

[kingkawn]

Great and informative response, thank you

[jakogut]

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

[15155]

> his air gun which fired 22 times at one charge

I think these might be classifiable as assault weapons.

[jakogut]

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

[icegreentea2]

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.

[jjk166]

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.

[kingkawn]

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

[dragonwriter]

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

[Glyptodon]

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.