The restriction on 7 rounds in the mag goes into effect in Mar I believe. Magazines of more than 7 rounds but less than 11 (the way it's worded in the law believe it or not) are legal if they are currently owned as long as you only put 7 rounds in the mag. As for buying the rifle, now is the time to do it because very shortly you won't be able to buy magazines that hold more than 7 rounds. You can purchase them up until Jan 2014 I believe but you can verify that by calling the hotline 1(855)LAW-Guns. They should be able to answer your question for sure, you could also try the
NY SAFE act FAQ on line
Stu