“Guns for criminals will be sold on the street like abused Drugs.”
They already are.
Ever heard of TOR? Every criminal has and they are probably more likely to buy them in cash, through the dark web or with some other non traceable way, rather than to risk having the government have any tabs on them.
Anyone with bad intentions can get a gun within a day or two. It’s the good guys who will have to wait for 911 to arrive when they have seconds to protect themself.