Almost all of the shootings that have taken place this year were done by individuals under the age of 30. This characterization can also be attached to the Columbine shootings of April 1999. It has been suggested by biologists and psychologists that mature adulthood is usually not achieved physically or emotionally during a person's 20's.
Second, making all Class 3 firearms illegal to own should be a formality. The right to bear arms doesn't include the right to own military style weaponry. For those who enjoy shooting these weapons, gun ranges could be allowed to carry them for recreational usage.
Additionally, Congress should enact a voluntary recall of any and all guns and should provide a tax credit equal to the purchase price for each gun voluntarily turned in.