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Comment by Ritsuko_akagi | Hacker News Reader

a gun is a sophisticated weapon? I though you could make one with a metal pipe, nail and springs; provided you have access to cartridges. could be wrong though.

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Well you can make a cannon as easily, but the BATF has been aggressive at pursuing people who discuss gun making, the more sophisticated (like 3D printing them) the more aggressive the pursuit. A project for recreating a black powder musket? Not a lot of heat. A project for a repeating launcher that lobs soviet era grenades while pulling the pins on exit, very aggressive pursuit.

It's legal to build your own guns.

3d printing isn't that sophisticated considering you can build a working AR with off the shelf parts, a drill press, and a hand router.

There's plans for an 7.62 Tokarev pistol based on the AK style action that have been floating around the internet since forever. No drill press or router required. Just a drill, file and some misc hand tools. The AK style action lends itself well to that kind of ghetto fabrication because it's a stamped receiver and machining tolerances can be described as "optional"

It's legal to build your own guns but people who disseminate info for how to do so have got in all kinds of legal trouble. Defense Distributed, codeisfreespeech.com, etc

Hey, I did that when I was 13 or 14. There was lots of ammunition lying around in the woods, if you knew where to look. Mostly 7.6 mm, but some 12.7 mm and 20 mm.

What woods were these that had 20mm cannon rounds scattered about?

Not far from Veliky Novgorod.

Probably means 10 gauge shotgun shells but I've never heard anyone call them "20mm"

edit: hmm, maybe that doesn't make sense since he also says 12.7mm, maybe he lives where there was once a war like m0zg says

20mm was a pretty popular caliber for AA guns, and you can often find them in the ground around the cities and military bases in Europe that have been heavily bombarded in WWII. In Europe it's a lot of fun to play with metal detectors since there's a lot of stuff in the ground around old cities, from ancient coins to more modern things like WWI and WWII bullets, broken bayonet blades, helmets, and all kinds of old metal junk.

This is true of nearly any country which had a real, actual, land war on its soil. Which is most of European countries, and especially the former USSR and today's Russia. As kids in Russia we burnt TNT for fun (or whatever the waxy thing was that's found inside artillery shells) and threw WW2 rifle rounds into bonfires. Only much later did I find out that TNT fumes are toxic.

TNT is indeed a very safe explosive. And yes, it burns ~like wax, but lots more sooty. Basically, detonation requires high-velocity shock. More even than blasting caps. You need a secondary explosive. Which, anyway, is why it's good for artillery shells.

Belated footnote: When the military run low on TNT and other "safe" explosives, sometimes they switch to stuff that's far more shock-sensitive, ages faster, and becomes very hazardous over time. So one key thing is knowing which types of munitions are ~safe to play with, and which are deadly.

Also, TNT releases NO2 when it burns (or detonates). Plus a bunch of ~toxic and ~mutagenic aromatic hydrocarbons, which end up absorbed on the soot. Some of which is respirable.

>Only much later did I find out that TNT fumes are toxic.

sounds like those self-made detonators we used to dispose the stuff of were a healthier choice :)

In any german city there is a good chance, that some forgotten bomb rots away right beneath the building you live, blowing up any second.

Excavator work here is something for heroes and suicidal people.

When I was a kid we used to pick up 50 Cal tracer ammo in the desert by the snake river. The story was that during training planes would pull most of their tracers out of ammo belts and dump them in the desert so they wouldn't have to put out wildfires later. 1970's

Sometimes I think 'hey, I had a pretty interesting childhood', and other times, I read comments like this one.

Sometimes it was too "interesting". I was 13 in 1962. A few years later, my parents worked at the UN in New York City. I met some people who were into LSD, and started smuggling it back home. When things got iffy, I ran away, and lived on the road. After a few years, I found a mentor, and got refugee status. Then college and grad school, and a ~middle class life :)

Out of curiosity, under the assumption you had kids, was your parenting style the anti pattern to helicopter parenting?

I don't think that I've had any kids. But yes, I would have been a laissez-faire parent, I think. Although it's possible that I might have become paranoid and over-protective (and over-controlling).

With a bit of work you've got the beginnings of a nice lyric there :)

People have suggested that I write an autobiography. But I'm more of a technical writer.

Not only is a simple gun, as you describe, able to be readily and easily made but, one can also make a sophisticated gun (AR style) through 3D printing or even using a relatively inexpensive CNC.

You can even build an AR-15 without a CNC machine. It's doable with a hand drill, although will look nicer and may function better if you use a drill press or router. There's a video on youtube of a guy that made an AR-15 out of beer cans, although he had some blacksmithing equipment if I remember correctly.

saw a guy who made one out of old casings.

Really cool. He had a milling machine though.

If this is the same video we're talking about, he 'just' melted down the beer cans into a block of aluminum and then machined a lower from it, right? (and he also made a video where he melted down spent brass and machined an AR lower from it) If so, that melting down can be done using $15 of home depot materials (metal bucket, thermal insulation wool or cement, 2 propane burners)

(DIY metal smelting/foundries are a great way to waste a few hours watching Youtube videos)

Guns are weird because to be effective they typically need to be rifled. You can obviously make a shotgun with some home depot pipe but the pressure bearing components of a gun can't be 3D printed. Even with 3D metal printing, you still need to machine the parts to final tolerances and your average garage setup is not remotely capable of rifling a barrel. Hence, when you hear about people 3D printing an AR, they're making the lower receiver which is both a trivially simple part, largely non load bearing, and also due to US law, the legal "gun" part of the gun. In most other countries the pressure bearing parts are the controlled items as those are the hardest to manufacture. In the US you can just buy an upper with the bolt, barrel, and chamber without a background check and manufacture the controlled lower however you want to obtain a complete rifle.

I guess this is all a long winded way of saying the 3D printing panic is both right and wrong but neither side is looking at it in a factual way.

True, but fin-stabilized sabot rounds (~darts) for the 12 ga shotgun are damn impressive.

https://www.youtube.com/watch?v=WGzgbXCrWHQ

You can rifle a barrel in your garage. Search youtube, there are DIY videos.

Btw, you need a rifled barrel to make accurate shots at long-ish distances. For close quarter combat a submachine gun with a smooth bore would do quite well. Something similar to this: https://en.wikipedia.org/wiki/Borz. Any machine shop can crank those out in numbers.

I was a bit simplistic given that I didn't expect all the HN gun experts to come out of the woodwork on this one but I'll bite :)

Yes, you can get by with a smooth bore but "long-ish" here is significantly less than buckshot range. To get really nerdy, if volume of fire (submachine gun) is going to replace accuracy, the difficulty in creating a reliable magazine dwarfs the difficulty in rifling and while I haven't tried, I don't think 3D printing has the tolerances to solve that...yet.

Yes you can rifle a barrel in a garage but you need real machine tools as well as some very specialized tools that you'll need to either acquire or build which kind of adds steps beyond "have machine tools" -> "make gun"

To crudely rifle a barrel you just need a press. Or you can make a machine like this: https://www.alloutdoor.com/2017/04/17/watch-homemade-barrel-.... I once saw a video of a machine which did not require any machine tools, you'd just make a guide and then manually cut the riflings. All you need there is a lot of patience.

For these designs you also do not need 3d printing at all. You just need suitable pipes, or sheets of metal that you bend and either weld or use fasteners to make the receiver. You are right though, designing and building reliable magazines is probably going to be one of the things that require a lot of attention to details.

There are books that have full blueprints for crude SMGs, here is an example: https://www.amazon.com/Do-yourself-Submachine-Gun-Lightweigh...

Depending on the magazine dimensions (single stack is hard) Reliable magazines can be largely 3d printed, as can the follower and the jigs used to bend piano wire into proper springs. The 3d.printed.mag will usually have less capacity than a metal one though.

Dunno if it qualifies as “sophisticated“ but original AK is designed to be made from like a piece of sheet metal and others pointed out you can rifle a barrel in your garage.

Sheet metal is actually harder to use than milled parts, it's just cheaper for mass production. The original AK was a milled receiver which they switched to stamped for subsequent iterations. Stamping metal with high accuracy is very hard and requires very special tooling.

> Stamping metal with high accuracy is very hard and requires very special tooling.

Only if you want to crank them out by the millions. As the "shovel AK" clearly demonstrates you can get it done more easily if you don't need to produce them at scale.

Sorry, no. It is cheaper in every way possible. The lower receiver is literally metal box with holes in it. You can hammer it out by hand and cut to size with a dremel. The most challenging parts will be smaller pieces (hammer, bolt etc) and all the tubing for the gas trap system (that one will actually require some welding). That’s if you want to build it entirely from Home Depot materials and tools for some reason (in the US only receiver is legally a “weapon”).

AK are harder to make at home because it's sheet metal. Requires welding and other harder work.

Vs buying an 80% blank, drilling a few holes, and then routing.

I see these 80% kits online that even includes the tooling you need to complete it. It’s so simple anyone could do it.

If compared to commercially available 80% lowers for ar, sure

There's always the classic shovel AK: https://www.northeastshooters.com/xen/threads/diy-shovel-ak-...

It has been demonstrated that you can fashion an AK out of a typical gardening shovel. https://www.northeastshooters.com/xen/threads/diy-shovel-ak-...

> your average garage setup is not remotely capable of rifling a barrel.

I'm going to argue the point. Yes, your average suburban weekend warrior won't have the stuff. But if you are even slightly into machining, you almost certainly can.

Practically every machining magazine will have at least one article about rifling in every issue.

Yes, you need a metal lathe and some tooling. Those are neither rare nor that expensive--and very old lathes and tooling work just fine.

The biggest problem a machinist always has is space for the equipment.

Yea, that's a fair point, it's not insurmountable. I responded to apr mentioning something similar but ultimately the point I'm making is mostly that the upper requires a small machine shop filled with mostly commodity tooling and the lower requires a file and a drill press or a cheap 3D printer.

At work so can't watch videos on rifling a barrel, but can this tooling also be DIY'ed? I imagine rifling is 'just' a matter of using a very thin, very long cutter on a suitable lathe, but then I would think it would be pretty hard to make such a cutter yourself.

haven't looked at rifling, but making single point boring cutters for a lathe isn't at all hard. you can just screw a carbide cutting insert onto any old piece of steel.

seems like you'd have stiffness problems for long barrels (?)

You could make a push broach that holds an insert (or make it out of HSS then press it through the barrel.

> At work so can't watch videos on rifling a barrel, but can this tooling also be DIY'ed?

There are a zillion videos on YouTube about this.

The hard part isn't the rifling, it's cutting the bore. After that, you can "just" push a rifling button through it and it will cut the rifling.

Amateur machinist here. I don't care about guns, so it would probably take a mistake or two, but I have zero doubt I could make a rifled barrel on the tooling down the block at my local makerspace. It isn't hard at all. (QC and repeatability are different topics, I'm not talking about commercial manufacturing.)

I can't do it in my garage, because I don't have one. My machines have to go up stairs in an urban walkup, so they're too small, and as mentioned, I have no interest in making guns anyway.

But yeah, a lot of people have both the skill and the means. Remember that people started making rifled barrels in the 1500s, a little while before we had CNC or overnight commercial-grade metal delivery.

All you do is make a die, harden it, and then carefully force it through the barrel? I guess?

I think the reason for going after lowers is because that's where, in AR pattern at least, the majority of components for auto-firing are mounted, whereas the upper may just have an extra notch or two etched in the bolt.

The auto sear (auto-firing part of the lower) is just a little lever hinged on a pin that blocks the hammer from moving momentarily. The two cuts that it interfaces with in the upper are somewhat more complicated.

I thought it also required some sort of twisted wire pin that interfaces with the sear and hinges off something built into the upper.

The majority of my firearm knowledge comes from that world of guns puzzle game so I'm probably very off on something, but I do remember there was a lot of going on in that area of the gun

Maybe you're confusing it with the fact that you can make a ghetto drop in auto sear out of a bent coat hanger?

Google "drop in auto sear" eventually you'll find something that explains the sequence of events of the trigger mechanism in sufficient detail.

No it's because the lower is legally the gun, because it has the trigger and hammer assembly in it. The whole rest of the upper half of the gun can be ordered online and shipped right to your house because it isn't legally a gun or the critical components.

Very different in Australia where every part of the gun is restricted. You can’t buy a single gun part and you certainly can’t buy ammunition without a license.

> your average garage setup is not remotely capable of rifling a barrel

Ehhh ... you talk a lot about 3D printing, but that’s not the only tool that people have in their garages. A huge number of people have metal lathes in their garages. I happen to have a small, CNC controlled metal lathe and mill in my garage. The whole setup cost me about the same as a high quality, rapid prototyping 3D printer (<4000USD). I am pretty sure I could make a firearm, in my garage, including rifling, if I was determined to do so.

Personally I have no desire to build my own firearms, because it’s illegal to do so in my country and it’s also extremely dangerous. But in many places in the US it does appear to be legal.

See P A Luty [0] and his submachinegun, made entirely from scratch using basic machine shop tools (i.e. not requiring a CNC machine, just a bench drill, hacksaw, angle grinders and various hand tools, see page 4 in his book. [1]) which was tested and confirmed as a viable firearm by the UK police (in order to prosecute him) although it doesn't have a rifled barrel...

0. http://armamentresearch.com/pa-luty-9mm-submachine-guns/

1. http://www.thehomegunsmith.com/pdf/Expedient-Homemade-Firear...

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