No, there is no loophole for replacement parts like there is in california. In NY the possession of a magazine over 10 rounds is soon to be illegal, regardless of when it was made. As for the 10 rounders, as far as I know, no manufacturer is marking ten rounders with dates so there is no way to prove you DIDN'T possess them prior to april 15...
Its a stupid law that will hopefully be overturned or ammended, but for now, anything over 10 rounds in any way shape or form is done...
