Salesmen at the biggest travelling gun fair in the United States have been caught selling powerful handguns to people who admitted that they would fail background safety checks.
Undercover investigators from New York City attended a Crossroads of the West show in Phoenix, Arizona, last month, posing as regular customers interested in buying semi-automatic handguns.
The show is held 50 times a year across the western states of America, and is annually attended by up to 600,000 people, which it claims is more than any other show in the US.
While private sellers are not required by law to run the checks, it would be illegal for them to sell guns to anyone they suspected of having committed serious crimes or being mentally ill.
Yet two of the investigators, who were sent by Michael Bloomberg, the Mayor of New York, told sellers: "I probably couldn't pass a background check", but were still sold guns, the investigators reported.
They made the purchases two weeks after six people were killed and 13, including Congresswoman Gabrielle Giffords, were wounded in nearby Tucson when a man opened fire in a supermarket car park.
One investigator was able to buy a Glock pistol and two high-capacity magazines – like the ones used by the Tucson gunman, alleged to be 22-year-old Jared Lee Loughner – without being subjected to checks.
"We have demonstrated how easy it is for anyone to buy a semi-automatic handgun and a high capacity magazine, no questions asked," Mr Bloomberg said on Monday.
"This country must take two simple steps to stop more of the 34 murders that occur with guns every day: make every gun sale subject to a background check, and make sure the background check system has all the required records in it."
Mr Templeton, 72, said that any vendors caught breaking the law in his shows would be "asked to leave or not allowed back".
But aides to Mr Bloomberg, who is campaigning for stronger gun control laws, said their sting operation had proved that the current regulations had "failed in states around the country." "If we don't fix it now, the question is not whether another massacre will occur, but when," said John Feinblatt, Mr Bloomberg's chief policy adviser.
The mayor has also called for police forces to boycott manufacturers that sell the controversial high-capacity ammunition clips, like the ones used in the Tucson killings, to ordinary customers.