The law is "assault weapons" may not be sold in the state of New York after April 15, 2013. Grandfathered "assault weapons" must be registered with the state police prior to April 15, 2014.
The lower receiver is the firearm. While it may not be legal to buy and sell them anymore, there is time left to have them registered as grandfathered.
No offense and none taken (̿▀̿ ̿Ĺ̯̿̿▀̿ ̿)̄