Why would anyone assume that the great majority of guns used in crime in Chicago are aquired legally? If you are a hood on the streets of south, you don't have to work that hard to get a gun.
Like Jim says, a similar boondoggle was attempted in Canada. Billions poured into it, not a single crime prevented or solved to show for it. Scrapped.
No need to repeat history or not learn from the mistakes of others.


Best,
Ted