So in other words, what else is new?
The danger if this passes isn’t that someone will be able to successfully implement some manner of system for identifying gun parts which will, apparently, rely on pixie dust and magic. In reality this will effectively prohibit 3D printer sales in California entirely because compliance is literally impossible. And it’ll and give overreaching cops and prosecutors yet another nonsense charge they can arbitrarily slap people with over “circumventing” this mystical technology which does not in fact exist if they, ye gods forbid, build their own printer.
It’s the same horseshit rationale as the spent casing “microstamping” fantasy that legislators have been salivating about for decades. It doesn’t work, it’ll never work, but that’s not going to stop them from wishing it does and therefore turning it into a defacto ban.
Keep in mind, California also has the precedent of their infamous approved handguns list, which notoriously does things like arbitrarily declaring that the black version of some model of gun is legal, but possession of the stainless version of the exact same gun is a felony. We’re not dealing with people in possession of any type of rationality, here.
Some of them certainly are. You can also get air rifles with built in “moderators” (i.e. suppressors) that are surprisingly quiet. Precharged pneumatic air rifles can be very powerful and also extremely accurate. I have a relatively cheap Hatsan that can, provided I’m using pellets that it likes, repeatably put pellets through the same hole in my target from as far away as I can get from it in my yard (probably about 20 yards) and do so about 30 times in succession before I have to pump it back up again. Its built in moderator makes it quiet enough at the muzzle that the sound of the hammer hitting the gas valve is actually louder than the report from firing.
Watch out: Researching this type of thing may send you tumbling down the rabbit hole of big bore air rifles and entice you to spend a lot of money. Don’t say I didn’t warn you…