To the OP, I have some good news for you, you're not limited to one gun in NYC- there is no limit restriction. The only restriction is that you have to get a safe for your 5th gun and have to wait 3 months after your first purchase to qualify for a second gun and then submit a purchase order and wait another 3 months or so for it to be approved etc. It's a pain but there's no limit. Good luck in getting your permit- I know it takes awhile.
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Here's a link to a nice compilation that someone did at the HK Pro forum:
http://hkpro.com/forum/showthread.php?t=78835
It's a very informative and well written thread, check it out.