Such bans would not be effective, nor would they be legal, nor ethical. Though the majority of people have a common interest in reducing the homicide and violent crime rate in the U.S even further, there are better ways to do so.
According to a CNN article, the average school shooter uses a semi-automatic gun. There have been 74 shootings that have been done since Sandy Hook. The majority of these shootings were done with semi-automatic guns. If we take these guns away, we can reduce the amount of school shootings happening.