They didn't enforce it because it would have caused a mass exodus of lawful citizens.
CWII will not start until the fascistcrats try a nationwide gun ban. Until then, you can easily leave the fascist states for a free state. I love Florida, but on the remote chance that criminal/fascist Gillum is elected, I will leave until sanity returns. Under no circumstances will I ever surrender my weapons to any government.
We in Virginia were well into the planning. It would have touched off CWII without a doubt, Mike Vanderboegh leading the way with all the 3%ers. It doesn't take a nation-wide ban because the others know that it will be them next.