Once again we see attempts to restrict the freedom of gun ownership. Do it under any pretext. I am against any tightening. I want to remind you that guns do not kill, and people who's weapons guide.
Yes guns don't kill but making them easier to acquire could certainly increase the number of bad tomatoes owning them. I don't live in the US but I heard you can even buy guns from WalMart. I was stunned when I first heard about that.
There's no denying America have a gun violence problem. The Swiss, I've heard is just as fierce with their right to own and carry arms but don't have as much problem with it as the US does.
Back to the blockchain tech, this does not necessarily restrict ownership but just make it easier to know who own what and how many. Maybe if teachers or doctors see something troubling with someone, they can check whether that person owns a gun so they can assess the risk that individual presents to others.
You forget that with the advent of 3D printers weapons have become even easier to do with their hands. Illegal guns exist in all countries and the problem is only in this. Legal weapon without technology easy to track and is usually not used in crimes.