[alid]

Microchip all guns? Or utilize nanotechnology to hook them up with a scannable barcode that can be scanned with a smartphone app? If it's not chipped, it's not legal. All police nationally should be equipped with necessary devices to scan guns on the spot.

Why would this help? There are currently millions of guns that have been subject to very little character checking or cross-checking. A gun census, of sorts, is needed. So I would suggest a harmonized shooter's license scheme and weapon registration scheme. Similar to a buyback - all gun owners have within a defined period to re-license (read: microchip) every one of their guns, after which time any unlicensed weapons (under the new universal license scheme) are illegal and confiscated. Part of this new licensing includes universal registration - so police nationally have records of all gun ownership and licenses - providing a uniform standard of safety across the country.

Bias: I'm Aussie, and in 1996 laws were introduced banning semi-automatic weapons in Australia (via a buyback scheme). In the 18 years before the law, Australia suffered 13 mass shootings - but not one in the 14 years after the law took full effect. Firearm homicides and suicides reduced dramatically. Life is safer without guns.

[alid]

Edit: I'm thinking we could use nanotubes, with a strength-to-weight ratio 117 times greater than steel.