Most crime, including mass shootings, are an outgrowth of material conditions in a given society. You can’t resolve those material conditions with reactive policies like you’ve outlined below, you have to act proactively. You want less white disaffected individuals shooting people, then work to bring those people into the fold. Ban right wing media that pushes entirely false narratives. Give everyone an irreducible minimum that gives them space to exist without constant coercion from society to self-enslave. Drop 70+% off the military budget and put ALL of it into social programs. Welfare, public housing, community centers, public works programs, etc. There’s infinite ways to resolve this, not a single one of them involves reactive policy.