You haven’t read the NY SAFE Act have you?
If you buy ammo in NY they want the type and serial number of all the weapon(s) in which it will be used noting the date of purchase and the name, age, occupation and residency of ammunition buyers – for each sale that police can later inspect “at all reasonable hours”.
You can buy whatever you want with no questions if you take a trip to a couple of states to your north (or East, if you’re in upstate).
Any New Yorker planning on stocking ammo should complete most of their purchases before Jan 15 ,2014.