There still are guns in New York.
The recent reports from NYC indicate that Bloomberg is allowing the city to slide back down to what it was before Rudy was elected mayor. Rudy's accomplishments as mayor were due to his focus on law enforcement, something his successor has failed to continue.
Indeed there are still guns in New York; the laws prohibiting them were in place long before Giuliani came along. Had he simply enforced the laws that were on the books, nobody would think of him as a gun-grabber. Unfortunately, his enthusiastic support for Clinton's anti-gun agenda (as evidenced by his lawsuits against gun manufacturers) tell the real tale.
I don't know where you came up with that "Rudy understands the 2nd Amendment" comment, but I question the careful wording. Note that it's not "Rudy supports the 2nd Amendment"... he "understands" it. Understands *what*, exactly? How far he can go in circumventing it by extra-legislative means?
It was in response to something about hunting and he went on to say he understood the 2nd Amendment - which I interpret to mean, he knows it is about more than hunting.