[zook]

Does "FF&C" give me the right to use my concealed carry permit in NY? If not, why not?

[Guillermo]

I don't know if it does or not, but I'm certain an argument can be made that it should.

One thing's for certain:

Any marriage made in an Elvis Chapel in Las Vegas is valid in Kansas. If it's valid in one state, it's valid in all others. This is not in doubt.

[SolidSupplySide]

Does "FF&C" give me the right to use my concealed carry permit in NY?

Perfect analogy. FF&C has never been used to make a state violate its own laws. Just as your CC permit is worthless in NY because of NY law, a gay marriage is null and void in any state in which gay marriage is not legal.