Why are 3D printers so relevant to plastic gun making?

[Machine_Elf]

@Jasmine

It sounds pretty horrific but, when you calmly consider the science, you realize that there is tremendous pressure involved in the explosion and release of a bullet. It would destroy a gun made out of purely plastic material.

Also, the kind of 3-D printer you would need to make a full sized weapon would cost many thousands of dollars. We have a 3-D printer in the library that can make objects the size of a shoe, and it cost $9,000. The materials are very expensive and, because of the constant and precise movements needed to create something, they break down A LOT.

Finally, I find it very hard to believe that it could even create a grooved barrel to begin with.

The kind of machines needed to make a conventional gun - mills, lathes, presses, etc. - cost tens of thousands of dollars and generally require a dedicated machine shop in which to house them, along with access to industrial power supplies. They also need substantial specialized knowledge and experience to program and operate them so that they produce the desired results. IOW, for a very long time it’s been very difficult for any random individual to make their own gun; the only feasible way for most people to obtain a gun has been to buy it through regulated official channels, buy it on the black market, or steal it themselves.

The plastic gun I’ve seen in the news recently could probably be made on a $300 3D printer that runs off of a standard wall outlet and sits on your office desk. This is cheaper than the computer most people already have in their home, and in fact cheaper than most conventionally-made guns. No highly specialized knowledge is needed, other than a short learning curve on how to use the printer’s software. The fact that possessing a plastic gun has been illegal for some time is little deterrent to a person who intends to use such a gun to commit a felony. A cash-poor thug who has street connections will still find it easier/cheaper to buy a black-market gun (or steal one) for his next liquor store robbery, so no change there; but with the advent of this new technology, a bullied suburban high-school nerd with no such street connections will now find it trivially easy to print a gun in anticipation of carrying out his revenge fantasy, and any terorrist who wants to sneak a deadly weapon into a secured area now has a much better chance of succeeding.

A 3D printer certainly could print a barrel with rifling grooves, but it probably wouldn’t matter. Since plastic isn’t terribly strong, I expect the barrel will have to be oversized to prevent any sort of interference fit with the bullet that could easily overstress the barrel. This means that the bullet isn’t moving down the barrel like a snugly-machined piston; it’s more like a kid spitting out a watermelon seed. Not that this matters. Rifling grooves and a finely-toleranced barrel diameter are only necessary for long-distance accuracy; they aren’t required for short-range lethality. Want to kill kids in a classroom, or passengers on an airplane? An unrifled plastic handgun will do just fine. The fact that it may shatter after just a few rounds won’t be a terribly big deterrent if you’ve got a few of them in your dufflebag, or a partner in crime backing you up.

[aruvqan]

@Kobal2

In the US, sure. In Sweden ? Germany ? Ireland ? The UK ? Not so easy to get your dirty mitts on a gun that’s not a sawn-off hunting shotty (and just owning one of those is a ticket to the slammer).

Not certain if this violates rules, but the classic zip gun was made from common hardware store items, a tube of piping of the correct diameter to seat a shell, with a grip welded or duct taped in place forming the ‘pistol’ format, and a sturdy elastic band to drive the short shaft of metal that is the firing pin against the primer element of the shell. I could walk downstairs in my barn and cobble one together in about 10 minutes of rummaging. Not elegant, but functionable.

Though honestly, a sheet metal brake, minimal tooling up and someone could crank out new fp45 liberator 45 cal singleshot handguns. Originally designed to be distributed in war zones, pick it uo and use it to kill someone for a better weapon.

[DPRK]

I thought real-life malefactors prefer to cause short-range damage by tossing a grenade in a room, hooking a bomb up to an alarm clock, that sort of thing, and that assassins and murderers prefer to use a weapon likely to actually kill the victim. Is the one-shot plastic gun thing a case of life imitating Hollywood?

[beowulff]

@DPRK

I thought real-life malefactors prefer to cause short-range damage by tossing a grenade in a room, hooking a bomb up to an alarm clock, that sort of thing, and that assassins and murderers prefer to use a weapon likely to actually kill the victim. Is the one-shot plastic gun thing a case of life imitating Hollywood?

I can see a one-shot plastic gun being very useful for aircraft hijacking, although somewhat less so these days with the locked cockpit door policy.

Also for gangland executions.

But, for general low-life criminals, a stolen gun is going to be more useful.

[EdelweissPirate]

@Chronos

Because people fear what they don’t understand, and lots of people know about 3D printers now but most don’t understand them.

This can’t be emphasized enough. People without a lot of mechanical understanding get excited about 3D printing, thinking, “You can print out any object you can imagine!!!11” In reality, you can print out any piece of plastic crap you can imagine.

Anti-gun people are often negatively excited; they grossly overestimate what a nefarious evildoer can do with a 3D printer. 3D printers are not Star Trek replicators. Direct-metal 3D printers exist, but they cost a whole lot more than the machine tools needed to mill a firearm conventionally.

There are two main reasons one might want to 3D-print a firearm:

• You like the idea of making/owning a firearm that the US government doesn’t know about; or
• You want a firearm that doesn’t set off a metal detector.

Most people who know guns and want to 3D-print a firearm are excited about the first reason, primarily because of libertarian political views, e.g., “The government shouldn’t get to know about my pistol on principle/so they can’t take it from me.”

Most people who don’t know guns and are worried about the 3D printed kind are worried about untraceable guns or guns that don’t set off metal detectors (or both).

But this is silly: you can buy AR-15 barrels and other parts anonymously on the internet all day long. The part the government considers to be the firearm is the lower receiver. This has a serial number, but it’s completely legal to buy a with a lower receiver that is already 80% finished from a machining standpoint. You can finish the rest with a drill press and have a completely untraceable AR-15 that is also totally legal. There’s no need to 3D-print anything.

In other words, you can already make a pretty decent assault rifle in your garage with a $150 drill press. That rifle is untraceable and entirely legal for non-felons to make and own. 3D printing doesn’t change that or make it any easier.

While non-technical anti-gun people may imagine that an “undetectable” plastic 3D printed gun is feasible, that’s just not true. People have made a few guns that work over very short ranges, but those guns become unsafe after (inaccuately) firing one or two rounds; true multi-shot guns are not practical. They will continue to be impractical for the foreseeable future, too. One could use a ceramic chamber/barrel, but fabricating high-strength ceramic parts is inherently difficult and expensive.

For what it’s worth, I’m a mechanical engineer with a lot of experience in 3D printing. I’ve also got a broad, solid understanding of firearms in general. While I’m an American and I have an interest in guns, my gun politics are roughly the same as those of an average European.

If 3D-printed firearms were a threat in any real way, I’d be shouting it from the rooftops. They’re not.

[EdelweissPirate]

@Machine_Elf

[snip] Want to kill kids in a classroom, or passengers on an airplane? An unrifled plastic handgun will do just fine. The fact that it may shatter after just a few rounds won’t be a terribly big deterrent if you’ve got a few of them in your dufflebag, or a partner in crime backing you up.

I respectfully disagree. A dozen plastic guns in a dufflebag wouldn’t help you hijack a plane; at most, you’d kill a dozen passengers. Post-9/11, the 100+ passengers would assume they had nothing to lose in attacking any hijacker, and they’d tackle you before you could fire all your guns. Swapping guns after firing makes you vulnerable, even when there are multiple hijackers.

A bullied kid could kill his bully with a printed gun, yes, but it would be unlikely that anyone else would die. If all school shootings happened with single-shot plastic guns, the annual death toll would be much lower than it is now. I mean, even one school-shooting death is too many, but I strongly doubt that the availability of 3D-printed plastic guns would make things worse. Guns already in the household (or in a friend’s household) are a much bigger concern for me.

[Leo_Bloom]

@aruvqan

Not certain if this violates rules, but the classic zip gun was made from common hardware store items, a tube of piping of the correct diameter to seat a shell, with a grip welded or duct taped in place forming the ‘pistol’ format, and a sturdy elastic band to drive the short shaft of metal that is the firing pin against the primer element of the shell. I could walk downstairs in my barn and cobble one together in about 10 minutes of rummaging. Not elegant, but functionable…

Query on this in “Carlo” thread.

[Hurk]

All the hype about printing guns is done by left-wing politicians and the media as yet another excuse to frighten ignorant people, so they can pass more and more restrictive laws against gun ownership.

Complete civilian disarmament is the goal, and they don’t care how many generations it takes to get there.

The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by menacing it with an endless series of hobgoblins, all of them imaginary. – H. L. Mencken

[Lizard]

@Hurk

A good friend of mine who owned a mold-making shop (now retired) got all the Fed and NYS licenses to manufacture handgun frames back in the '80s and '90s. It was just a hobby item, they had no intention of selling any. They ended up making about 25 Colt .45 ACP clones out of titanium, all machined with CAD-CAM.

They spent a LOT of spare hours in the project, but it worked out. As it was, they were so worried about legal issues down the road they wouldn’t even sell me one.

Did you at least get to shoot them? I’d be very interested to know how a titanium frame handled in terms of rigidity and recoil. Did they stress-test these frames? How expensive/easy to get was the base material? Questions abound!

[Hurk]

@Lizard

Did you at least get to shoot them? I’d be very interested to know how a titanium frame handled in terms of rigidity and recoil. Did they stress-test these frames? How expensive/easy to get was the base material? Questions abound!

Nope, I never shot one. I don’t think they got all 25 assembled with all the parts to make complete guns, but they did have a few that worked.

Titanium is extremely strong (WAY stronger than plastic) so I don’t think that was ever an issue. Being light, they probably did recoil more than the heavier steel frame would. I know they made at least one with a 7" (maybe 8?) barrel and slide that functioned. I guess it was quite the conversation piece at the local gun range.

This all happened in the late '80s thru the '90s. There were no CAD files anywhere for 1911s but they did manage to get a blueprint somehow. From that they created a CAD file and machined them from that. I know they made a couple of aluminum (easy to machine) test frames first, to tweak in the machining process.

Getting the titanium material was probably the least of their worries.

[Darren_Garrison]

I guess custom-made titanium guns are okay for the masses. Me, I’d prefer these.

[Colibri]

@Hurk

All the hype about printing guns is done by left-wing politicians and the media as yet another excuse to frighten ignorant people, so they can pass more and more restrictive laws against gun ownership.

Complete civilian disarmament is the goal, and they don’t care how many generations it takes to get there.

The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by menacing it with an endless series of hobgoblins, all of them imaginary. – H. L. Mencken

Moderator Note

Hurk, political jabs are not permitted in General Questions. No warning issued, but do not do this again.

Colibri
General Questions Moderator

[Leo_Bloom]

WASHINGTON STATE TOUGHENS GUN LAWS, BANS ‘GHOST GUNS’

Democratic Washington Gov. Jay Inslee signed a series of gun bills into law, including a law banning 3D-printed and other “ghost” guns.

Seven gun-related bills with a variety of gun access restrictions became law, including gun removals by police for certain people with restraining orders against them and domestic violence suspects, as well as tightened laws for minors, The Associated Press reported. The bills were passed by a Democratic-majority legislature.

…

Ghost guns, named because of their difficult traceability, are either plastic guns constructed with 3D-printers and able to evade metal detectors, or homemade guns built from kits available online or at gun shows that do not have serial numbers.

The laws prohibit guns without a serial number and calls for background checks for people who buy gun-making kits.

[Son_of_a_Rich]

@sweeteviljesus

Nitpick: Barrels are made using machine tools made for deep-hole drilling, not ordinary lathes or mills. Rifling is done using other specialized tools such as sine bar riflers. Really fancy shops will hammer forge the barrels onto special mandrels which have a negative of the rifling on them. You could also go old skool. Check out The Gunsmith of Williamsburg.

Rob

But couldn’t you still make a barrel with an ordinary lathe? Sure it would be smooth bore, but it would still shoot, albeit lacking the accuracy of rifled bores, right?

[engineer_comp_geek]

@Son_of_a_Rich

But couldn’t you still make a barrel with an ordinary lathe? Sure it would be smooth bore, but it would still shoot, albeit lacking the accuracy of rifled bores, right?

Sure. And adding rifling isn’t that hard. There are some fairly easy methods you can use with very simple homemade tools to rifle barrels. If you know how to use a lathe, you probably have the skills required to rifle your own barrels.

[drachillix]

@engineer_comp_geek

Sure. And adding rifling isn’t that hard. There are some fairly easy methods you can use with very simple homemade tools to rifle barrels. If you know how to use a lathe, you probably have the skills required to rifle your own barrels.

The metal lathe at our local makerspace is a gunsmithing lathe. It has features built in for cutting rifling with the correct tooling added.

[Chronos]

Huh, really? All of the makerspaces around here have pretty strict “no weapons” rules. Which I imagine are mostly an attempt to assuage the 3D PRINTED GUNS!!! panic.

Of course, I haven’t found a public makerspace around here that has a metal lathe at all. Annoying, as I have a few (non-weapon) projects that could use one. That, I assume, is just a matter of cost and demand: A wood-milling machine is cheaper and gets more use.

[Melbourne]

@Napier

I hear 3D printers are creating a new threat because they facilitate making plastic guns that aren’t detectible with metal detectors. I don’t get it.

That’s not how it’s reported here (aus). Which, to be clear, is by re-publishing American reports.

The reports that were re-published around here were mostly that 3D printers created a new threat by allowing people to buy and own gun parts that did not constitute ‘a gun’ as legally defined, then assemble guns using the ‘gun parts’ and 3D-printed receivers, thus creating an easy out-of-channel path to gun ownership for people who do not have machine-work skills.

[HurricaneDitka]

@Melbourne

That’s not how it’s reported here (aus). Which, to be clear, is by re-publishing American reports.

The reports that were re-published around here were mostly that 3D printers created a new threat by allowing people to buy and own gun parts that did not constitute ‘a gun’ as legally defined, then assemble guns using the ‘gun parts’ and 3D-printed receivers, thus creating an easy out-of-channel path to gun ownership for people who do not have machine-work skills.

To the extent that one considers that a “problem”, it’s one that preceded 3D printing. There was a guy who made a mold for AR-15 lowers out of Legos, and was pumping out brightly colored plastic ones he made with his Lego mold and urethane plastic. Instructions are available online.

[GaryM]

@HurricaneDitka

To the extent that one considers that a “problem”, it’s one that preceded 3D printing. There was a guy who made a mold for AR-15 lowers out of Legos, and was pumping out brightly colored plastic ones he made with his Lego mold and urethane plastic. Instructions are available online.

I’ve made a few of those. They work fine and can be made in different colors. I purchased the mold set rather than building my own from Legos.