Aside from trashing the second amendment nothing that has been proposed has a chance.
The gun supply genie is out of the bottle. The magazine genie is out of the bottle, short of Gestapo type home searches and summary executions for violators there is never going to be a supply solution.
Stop and frisk has proven to work. There is room for advancement in information sharing wrt mental health issues. Tougher gun laws for violators upon conviction will add a little. Gun safety classes and education maybe even mandatory like Switzerland would help a great deal. We never had this degree of a problem before liberalism became the norm.