If law enforcement put as much effort into stopping the proliferation of guns, as opposed to just catching individuals (particularly poor and of color) with unregistered guns, there would be less guns available.

There's a youtube video somewhere, I'll try to find it, of a community meeting on gang violence in some city, I don't remember. A woman asked a speaker in law enforcement how guns get onto the streets. The officer replied that most are probably just stolen from small retailers, or relatives, friends, etc.

The audience laughed, because, obviously, the massive quantities of assault weapons on the streets are not being stolen from grandma's house. The officer then gets frustrated and replies, "We don't know, and we don't care. We're going after the gang bangers who are destroying your community. We don't care how they get their weapons."

He was resoundingly booed, as he should have been. This kind of apathy and laziness in law enforcement is as much to blame for inner city violence as anything.