He is starring in the group's new ad and pushing the mayor's agenda.
"Do you support having a background check for every single gun sold?" he said. "And ideally, I would like to hear them to say yes."
For months, Bloomberg has railed against President Barack Obama and Mitt Romney for failing to take a clear position on illegal guns.
"I think both of these people that want this job have an obligation not to duck this issue but to tell us what they are going to do," the mayor said in July.
To Bloomberg, their answers haven't been satisfying.
"A lot of gun owners would agree that AK47s belong in the hands of soldiers, not in the hands of criminals," Obama said in July.
"I don't happen to believe that America needs new gun laws," Romney said in July.
It's a dissonance some say is to be expected.
"While mayors, especially Bloomberg, have been outspoken on this, very few statewide officials have been because the rural areas and the suburban areas have a different take, largely influenced by the NRA."
Bloomberg's agenda has also seen some failures closer to home. Legislation he pushed for to require microstamping technology is currently stalled in Albany.
That bill would require bullet casings be imprinted with serial numbers, making them easier to trace.
It's made the mayor some enemies.
"Look what the man has done in New York City," said Tom King, the New York State Rifle and Pistol Association. "You can't have a sugar drink over 16 ounces. I mean, come on, what is that, is it the People's Republic of New York City?"
Bloomberg's message hits home with some people. It was enough to make Barton relocate.