The NRA apparently was unaware that the University of California professor behind the study -- himself an NRA member -- received the email discrediting his research.
Garen Wintemute, director of the UC Davis Violence Prevention Research Program, conducted a survey of 1,601 federally licensed gun dealers and pawnbrokers across the country in 2011. Fifty-five percent of respondents supported comprehensive background checks.
But when Wintemute started interviewing gun vendors for his study, he received an email essentially advising him against himself.
"If you are a federally licensed dealer in firearms, you may recently have received a survey questionnaire from gun control supporter Dr. Garen Wintemute, of the University of California, Davis," said the email, obtained by Al Jazeera.
"Why is Dr. Wintemute sending the survey?" it continued. "Consider the source. Over the years, he has received hundreds of thousands of dollars from anti-gun organizations to conduct 'studies' designed to promote gun control."
Wintemute said he never received any money from anti-gun groups. "I've turned it down, in fact," he said.
Wintemute said he did not respond to the email. "The positions taken by the leadership of the organization," he said, "don’t represent NRA members."
The NRA was not available for comment at time of publication.
Wintemute completed the study, despite the opposition. In 2011, he found that a majority of gun shop owners supported comprehensive background checks that include provisions barring people from purchasing firearms if they have a history of everything from mental illness to alcoholism-related crimes.
"I suspect that the levels of support we got in 2011 would probably be higher if they were published today," after mass shootings in Aurora, Colo., and Newtown, Conn, he said.
Steve Schneider, owner of firearm vendor Atlantic Guns in Silver Spring, Md., pointed out that "the federal background check is already in place," though he would not talk about his personal views on gun-sale regulations.
According to the report, only 16 states nationwide have laws mandating background checks for private purchases -- mostly at gun shows and over the Internet. Private vendors, who Wintemute estimates sell some 40 percent of firearms, are not required by federal law to perform background checks.
Wintemute said that, although it would mean more paperwork, a majority of vendors support a system where "private purchases would have to be routed through a licensed dealer" for paperwork to be done.
"The last thing they want is for a gun to go out of their store to be used in killings and suicides," he added.
But gun-control advocates suggest there may be another reason for licensed gun vendors' support for background checks.
"Because of the loophole on background checks still, (the licensed dealers' private) competitors don't have to comply with the same laws that they have to comply with," said Monte Frank, the legal counsel for anti-gun-violence group Newtown Action Alliance.
Last December, 20-year-old Adam Lanza shot and killed 26 people at Sandy Hook Elementary School in Newtown, Conn., where Frank's daughter once went to school. Twenty of the victims were children.
"If you go to a gun show," Frank said, "and at one table there's a federally licensed gun dealer who has to comply with federal law, if someone goes to that dealer and fails a background check, they can go to the next table, with no license, and they would not have to conduct a background check."