You can apply to your county for an assault weapons permit, but they are rarely issued.
If the weapon is a collectabl or sentamental value, find a gun shop or trusted Friend/relative to store it for you out of state. An old friend of mine(he is in his 80s) was given his M1 Carbine by the US Army after he fought in WW2. He had it many years. He wrote a letter to then governor Florio to take this gun off the proposed ban back in 1990. He was denied the request(obviously), and was told to have it de-activated. Mike was a WW2 hero, facing Nazis in Europe. He protected fuel planes when they landed. He saw much combat. He is also Jewish, and this gun meant the world to him, meaning it protected his Jewish heratige. Luckily he is no fool to surrender his gun, It is safely tucked away in PA, at his daughter's home.