Fixxer:
The NY ban is aslo a STATE ban, in additiona to a city ban. This AWB is permanent, and is state wide.
You will not be able to purchase the new 'no-ban' rifles in NYS. However, you can find the odd pre-ban/post-ban. I suspect the westchester dealers are rather accustomed to NYC crowd trying to cirumvent the NYC legislation. I also rather strongly suspect that most dealers are dumber than dog shit when it comes to legislation: Most seem to have no real idea of what the law really is. as a result, your options are going to vary.
I think you may wish to travel farther north. Most upstate dealers don't give a rats ass about NYC. If you are a NY state resident, have appropriate ID, and can pass NICS, you'll walk out with an AR of some legal (in NYS) configuration. What happens to it after that is your problem.
Just remember, we are dealing with THREE levels of AWB here. The expired federal law. The still relevant State law (limits options to Pre-ban, post-ban, but has no permit requirement), and the NYC Law. Stpe outside NYC and no one cares what NYC does.
Frozenny