An Australian told me that they passed a registration law. Then they went door to door and collected all the guns. I saw a photo of really nice Spencer rifles (US Civil War)being crushed by a road roller.
In NY they will do this very gradually.
Whenever you are stopped for anything by the police, they will check to see if you bought an “assault weapon”, and try to enforce the SAFE act.
Whenever you do anything related to taxes or vehicle registration, they will check.
Any interaction with the state will result in a check regarding “assault weapons”.
They will probably do things like deny vehicle registrations until you turn in your illegal weapons, or satisfy them about your weapons.
It will be a very gradual process, not an all at once move.