The argument of guns and ownership is drawing to a quick close. I've heard the discussions and law enforcement is VERY concerned that in the next 20-30 years, you'll just be able to print one.
Now of course that's just a simplified statement, to print one out. But it is a real, upcoming problem. Currently magazines can be printed. Not some speculation, or plans, but fully functional rifle magazines.
This is what people are doing in their free time. Imagine with crowd sourcing and 3d printers being in the price range of a couple of hundred bucks.
Just download the torrent for an AR-15 and print the thing. Need a 100 round magazine, just download it.
How do you stop something like that? It's not going to work to simply ban them. Yeah yeah, but you still have to have a barrel and bolt! Think what they'll be able to print in 20 years when this stuff is as common as a flat panel monitor. It's coming, and why law enforcement and government is concerned.
There's going to have to be a shift somewhere in how crime, mental illness and drugs are treated in the future. Simply banning firearms, even if you were able to make existing ones go "poof" into thin air, isn't going to prevent the future.