It is an article of faith that closing the “gun-show loophole” would make America a safer place. But that is what it is: faith. In 2008, three criminologists (one of them not at all friendly to guns) studied the effects on murder and suicide rates in California (which prohibits private sales without a background check) and Texas (which does not). They looked at homicide and suicide rates for adjacent ZIP codes for a week after gun shows. They found no change in suicide rates, and in Texas, which has no restrictions on private party sales, a small but statistically significant reduction in gun homicides.
This might seem surprising, and at first glance, it is. Except for one little detail: Criminals appear not to buy guns at gun shows, because guns are expensive. It is so much cheaper to steal guns instead.