Unfortunately, "assault" weapons bans have been upheld by the US Supreme Court as being constitutional.
I am not sure a requirement for grandfathered weapons to be registered has ever been tested in court, though. That is what is at issue here.
ARs have less power than a deer rifle or several handguns. The left has jumped on the term assault without even understanding that particular rifle. Many even think that a .223 is fully automatic.
Look, you can empty a 30 shot clip in under 10 seconds. That is effectively a machine gun. Not good for accuracy, but cleans out a grade school classroom or shopping mall rather effectively. Now as for the power of the .223, with the type of bullet that Lanza used, they do horrible damage.
Now I have a solution for the present owners of the assualt weapons. If you want to take the guns out of the house, you have to have the same license as required for a Thompson Machine Gun. But if you keep the gun in the house, then there is no problem. If you are caught with the gun outside the home or your property without the license, you are jailed, and have a felony on your record, with no right to a firearm for the rest of your life. The second law is that if you store your weapons where someone can easily get them, someone takes them and uses them in a crime, you own that crime. It is called accountability.
Oh yes, and I have been a gun owner since I was 12 years old. And am able with both rifles and handguns.