In a move reaching far beyond the New York City mayor's turf, Bloomberg sent private, undercover investigators to an Arizona gun show. And Bloomberg says his agents found sellers peddling their wares even after buyers said they likely wouldn't pass a background check. 

The sort-of sting operation is Bloomberg's latest tack in pushing for more and better background checks in the wake of the Tucson shooting.

"We have demonstrated how easy it is for anyone to buy a semi-automatic handgun and a high capacity magazine, no questions asked," he said.

Bloomberg unveiled a series of videos Monday, shot at the Jan. 23 Crossroads of the West gun show in Phoenix. The videos were shot by undercover investigators working for a private company, Kroll Associates.

In one video, a man trying to buy a gun tells the dealer he probably couldn't pass a background check. The dealer, undeterred, sells the man a gun anyway.

This isn't the first time the Bloomberg administration has hired P.I.s to bolster the gun control push. Using city money, he has dispatched Kroll investigators to gun shows in other states, to determine whether dealers would sell guns to people knowing their backgrounds were questionable.

Since the Jan. 8 Tucson shooting, Bloomberg has tapped Daniel Hernandez, the intern credited with saving Rep. Gabrielle Giffords's life, to support the cause, holding frequent news conferences and touting statements of support from various elected officials and families affected by gun violence."