Senator Chuck Schumer, D-NY, whose staff made that discovery last week, offered one reason.
"When so many of the guns used in crime come from so few of the gun dealers, it is a pretty good bet that they aren't obeying the law,Â" Schumer said. Â"Some may be doing it willfully, some may be doing it by mistake. But it's a good bet."
Specifically, Schumer found that just over 1,100 gun dealers were responsible for the sale of 34,626 guns later traced to a crime last year. He argues that so many sales to so many bad guys can't be a coincidence, reports CBS News Correspondent Jim Stewart.
But given the fight in Congress, gun sellers say the timing of the report isn't a coincidence either.
Hayward Long, whose store, Blue Ridge Arsenal in Chantilly, Va., was not cited by Schumer, argues gun traces can be misleading.
"Because a gun is traced to a legitimate gun dealer does not mean that they were doing anything illegal or inappropriate," Long said.
Take Long's own experience: someone stole 29 guns from his store and, given how they disappeared, it's no surprise some of them turned up at crime scenes.
Plus, many of the nationÂ's firearms dealers aren't dealers at all, but hobbyists, leaving the world of discount sales and high volume to a few big dealers.
"It's not the dealerÂ's responsibility. It's not Ford's responsibility to follow their cars through to someone who gets drunk and runs somebody down. It's the same thing with firearms dealers," said Sanford Abrams, who sells accessories to gun stores.
Still, it's a good bet these findings will cause trouble for the firearms manufacturers, who have long argued they have no way of knowing what happens to their product after they make it. Now, they do. And the answer, it appears, can be traced back to just a handful of America's gun sellers.