Now it gets more interesting...
Knowing exactly who owned which firearms, the Nazis had only to revoke the annual ownership permits or decline to renew them.
http://jpfo.org/filegen-a-m/GCA_68.htm
I can't speak to any other similarities, but, I have a close friend who is a retired NYC Police Sergeant and he said one of the reasons he elected to retire and leave NYC was that the Department enacted a policy of refusing to renew gun licenses and then, after waiting a certain amount of time, notifying the registrant's that he had to turn in the weapon or face confiscation or penalties.
As my friend told me, "he saw the handwriting on the wall" and left.