More than 400 guns, including these three, were turned in during a Dallas gun buyback program in January. But determining the effectiveness of such programs is difficult due to limits on gun-related research.
The characteristics of gun violence in the U.S. are largely unknown because key federal health agencies have been banned from conducting such research since the mid-1990s.
President Obama, however, wants to change that.
In presenting his plan to reduce gun violence last month, Obama said he would order the Centers for Disease Control and Prevention to resume scientific studies of the issue.
"We don't benefit from ignorance," he said.
On Monday, however, the president acknowledged in a speech to the Minneapolis Police Department that he might be in for a fight. "Because for a long time, even looking at the evidence was considered somehow tough politics," he said.
Indeed, opponents on Capitol Hill are already making their concerns heard.
"Gun violence is not a disease," Iowa Senator Charles Grassley, the top Republican on the Senate Judiciary Committee, said in a recent speech on the Senate floor. "And lawful gun ownership is not a disease. It is a constitutionally protected, individual right."
But gun researchers say it is long past time that the research resumes.
"We really don't know some of the answers to the critical questions we need to know about [gun violence] in order to have more effective law enforcement and more effective public policy," says Harold Pollack, co-director of the Crime Lab at the University of Chicago.
At the lab, most research on things like underground gun markets and strategies to prevent gun violence has to be done with nonfederal funds. "There's been a chilling effect brought about [by] the constraints that the president spoke about and by the political history of this debate at CDC and elsewhere," Pollack says.
RAND Corp.'s Dr. Art Kellermann, a health policy analyst, is well-acquainted with the political history of the debate.
Kellermann grew up with guns in East Tennessee. "Having a gun in your house was about as controversial as having a washing machine," he says. He says he was quite familiar with the idea of keeping a gun in the house for protection.
"But as a young ER doc, I wasn't seeing too many bad guys shot by homeowners," he says. "I was seeing kids shot by another child while they played with a gun they had found. I saw spouses who had shot one or the other in a family dispute. And I saw older individuals and sometimes teenage kids who used a gun to either take their life or attempt to take their life."
So he and several other researchers set out to study what they saw as cost-benefit analyses of the dangers of keeping guns, particularly loaded guns, in the home.
The findings were all strikingly similar. "On the balance, the risks of a tragedy in the home — a homicide or suicide — were actually increased if a gun was kept there rather than not," he says.
Gun advocates blasted the research.
Michael Hammond, legislative counsel with the group Gun Owners of America, says it appeared as if the CDC "was going to ... basically issue politicized studies with taxpayer funding concerning the Second Amendment issues."
The group first tried to defund the agency's entire injury control center, though research on gun violence amounted to about $2.6 million of a $43 million budget.
The following year, a compromise of sorts was reached. Congressional funders took the $2.6 million the CDC had been spending on gun violence research and ordered that it be used instead to study traumatic brain injury.
It was very clever, says Rep. Rosa DeLauro, D-Conn., now the ranking member of the appropriations subcommittee that oversees the Department of Health and Human Services budget. "How do you say no to traumatic brain injury?"
But opponents of gun violence research also added language stipulating that "none of the funds made available for injury prevention and control at the Centers for Disease Control and Prevention may be used to advocate or promote gun control."
Obama says his order that the research resume is premised on the legal opinion that gun violence research isn't the same as advocating or promoting gun control.
That's what researchers have always claimed, too. Public health research, they say, is based on making things safer, not on taking them away.
"It's ironic if you think about it," says Kellermann. "The last 20 years we've made spectacular progress with car crashes ... in reducing drownings, smoke inhalation from house fires. And yet we've not banned matches, swimming pools or automobiles."
But neither the CDC nor researchers wanted to take a chance testing the limits of the research ban, says DeLauro, and that essentially shut the research down.
Lawmakers have since expanded the ban — today it covers not only research at the CDC but also other agencies at HHS, including the National Institutes of Health — and they even added anti-gun control language to the 2010 Affordable Care Act.
HHS Secretary Kathleen Sebelius said the department is "committed to re-engaging gun violence research" at CDC and NIH.
But the only real way to ensure the research restarts is for Congress to drop the existing language from the annual spending bill and restore funding.
A spokesman for Georgia Republican Rep. Jack Kingston, the new chairman of the HHS spending panel, said the chairman is planning to hold hearings on the matter. "If CDC can show they can do nonbiased and nonpolitically motivated studies, that's something he'd be interested in," the spokesman said.
But like everything else gun-related in Congress, nothing is guaranteed.