New York City spent $1.5 million to send private investigators to make what it considers illegal gun purchases at seven gun shows, including one in Reno in August.
At the Big Reno Show on Aug. 16-18, the investigation firm used hidden cameras to record the purchases of four semi-automatic handguns from unlicensed sellers.
At a Wednesday news conference, New York Mayor Michael Bloomberg, an independent, said each buyer asked if there was a background check and when told there wasn't, replied with something like: "Good. Because I probably couldn't pass one."
Bureau of Alcohol, Tobacco, Firearms and Explosives officials said they wouldn't investigate the Reno case because it involves an unlicensed person making a sale, what they call occasional sellers, spokeswoman Nina Delgadillo said.
Reno police could not be reached for comment.
Congress has left it up to states to regulate gun show sales, but Bloomberg wants federal action. He said he was sending the report to every member of Congress to "embarrass them into action."
Bloomberg also said reports were sent to the mayors in each city where the stings took place. Reno Mayor Bob Cashell was not available for comment.
Lou Fascio, the promoter of the Big Reno Show, did not return calls seeking comment.
The New York report said investigators from Kroll Inc. purchased four guns in Reno: a Beretta Px4 Storm .40-caliber for $598, a Llama Minima X45 subcompact .45-caliber for $500, a SIG Sauer P230 .380-caliber for $725 and a Jennings 9mm for $400.
The sellers were not named, but two of the photographed transactions were made public. Video cameras were hidden in baseball caps and purses, and microphones were in wristwatches, Bloomberg said.
In one Reno sale, the seller confirms no background check is required.
"No tax. No charges. Nothing. Just $500 and it's yours, and out the door you go," the seller said.
"Just gotta have a Nevada driver's license," a second seller from Reno said.
Purchases at other gun shows included SKS assault rifles, the report said.
At six gun shows, investigators tried to make straw purchases in which one person fills out the paperwork and buys a gun for someone else. There were no attempted straw purchases at the Reno show.
In the straw purchases and sales by unlicensed dealers at all gun shows, 19 of 30 sellers made illegal sales, Bloomberg said. Four of five sellers in Reno sold guns to people who said they couldn't pass background checks, the report said.
The National Rifle Association said Wednesday that Bloomberg's sting was nothing more than a publicity stunt.
"If he was serious about curbing crime, he would have cooperated with local law enforcement authorities instead of grandstanding at a press conference," NRA spokesman Andrew Arulanandam said.
ATF spokesman Drew Wade said the agency was reviewing the report and declined to comment on its conclusions or whether the city had acted appropriately.
The Associated Press contributed to this report.