> You basically just need a metal tube, and well... a pipe from home depot does that much better than trying to 3d print something much less reliable.

Why would you buy a pipe at Home Depot? A gun barrel is not a firearm, and is not required to be registered or serialized. You can drive to Arizona or Nevada and buy an actual barrel, with rifling, manufactured to meet well-known specifications, without showing an ID. Until this year, you could have a barrel shipped to your California residence without an ID. There's no need to build the Shinzo Abe contraption.

> So my assumption is immediately that some relatively large lobbying group feels threatened by 3d printing, and is using this as a driver to try to control access and limit business impact.

Occam's razor. This isn't a shadowy manufacturing cabal, threatened by 3D printing. Gun control lobbyists are trying to prevent the printing of handgun frames and Glock switches, because they're the easiest parts to print.

> Either way, this is bad legislation.

California legislators haven't met a bad gun law that they don't like.

Reminds me of the sUAS legislation crushing the R/C flying hobby. Vague allusions to "safety" are constantly being thrown around, but in fact it seems that big companies are lobbying to claim the airspace for drone delivery and similar autonomous BVLOS operations.

The only thing you need to make is the "lower" or whichever part the ATF constitutes as "the firearm" I've seen someone take a shovel and turn it into an AK. Once you have the "firearm" part of whatever gun you're building, the rest of the parts can be shipped to you in most of the country (idk about CA, and NY though) and you can easily assemble the rest of the gun.

Like you say, you just need to build a key metal piece, and voila, the rest is buying parts that can be delivered to you, in some cases fully assembled.

You could also just buy black powder guns directly to your home (idk about in CA or NY though) which are not treated as "firearms" by the ATF.

The only people shooting 3D printed guns are enthusiasts usually, who have other guns.

I'm not on top of the current SOTA in 3d-printed guns, but the way it typically was done in the past is that you don't actually 3d-print all of what you or I would call a complete gun.

The barrel will be metal. In designs made for the US market, it will almost certainly be an actual manufactured gun barrel, since gun parts other than the receiver are not closely tracked in the US. In designs for Western Europe, the metal parts will be either milled or things you can buy at the hardware store[1].

The barrel and chamber being made of something tougher than you can get from an FDM machine is basically a requirement for making a gun that doesn't explode in your face when you shoot.

1: Here's an image of all of the parts going into a gun designed to be made in the EU. Per the wikipedia article, the barrel rifling can be added with electrochemical machining https://en.wikipedia.org/wiki/FGC-9#/media/File:FGC-9_Compon...

Not that I support any of these obviously stupid bills but:

> what's special about 3d printers?

They can make guns made out of plastic and metal detectors are kind of the primary way we try to find guns on people.

You are probably right about the lobbying group, I agree.

Edit: I'm not saying it makes sense, but this is the angle the congress folks are taking, sheesh.

> any real attempt to regulate guns

Any real attempt would need to be at the national level, not that I would advocate for it, but it's simply a pipe dream to create a "gun free zone" in a country with 100s of millions of firearms. There are plenty of gun enthusiasts in California, they just don't flaunt it or talk about it.

> So my assumption is immediately that some relatively large lobbying group feels threatened by 3d printing...

I'd say the real groups behind this are the anti-gun ideologues, the "do whatever it takes to stop my panic attacks over Bad Things maybe happening" left-wing control freaks, and the old-fashioned "big state" authoritarian crowd.

And the only reason they're paying attention to 3d printers is that some pro-gun ideologues and provocative makers have been talking up the concept of 3d printing guns.

whats special is speed and consistency.

when you manufacture a personal firearm, it is supposed to be yours, for your use. the 3d printer aspect, makes it possible for a group to print large quantities of receivers, under the radar, to be combined with "accesory parts" close to "drop-in" assembly style.