Instead, There should be strict background checks involved when purchasing a firearm. Mental illness of the perpetrator is the cause of gun related violence - not the weapons themselves. Guns are very useful for self defense, Like if someone robs your house - you wouldn't be able to fend off an armed robber without a firearm. If a person has a history of psychopathic traits or an extensive criminal background then they should be prohibited from purchasing weaponry - it's that simple.
The U. S has so many guns that it wouldn't have a very strong effect. Lots of people would still get weapons illegally, And because there are so many guns, Getting them illegally wouldn't really be that hard. And besides, Majority of gun violence doesn't even involve legal guns, Most of them are illegal guns anyways.
It's too general of a question really. Machine guns should be "heavily restricted" as they are now. Certain types of guns should be banned, Such as sawed off shotguns as they are now. But not ALL guns need be banned. Perhaps more restrictions need placed on person who possess guns illegally or for nefarious purposes.