Guns have two enemies. Rust and politicians.

In Maine to get a permit to carry concealed you must pass a background check, and demonstrate your ability to handle a hand gun. My law enforcement background is proof enough of that, but the check still takes about a month. There are 10,000 permits in Maine and I have never heard of one being taken away.

To buy a long gun from a dealer you simply need to pass an FBI check which takes about 10 minutes.

The big loop hole is gun shows and private sales. No one has figured out how to stop nuts from buying guns that way.