There's 0 evidence the 94 ban had any effect. Violent crime was already on a downward tend, and when the ban sunsetted 16 years ago, that downward trend continued until the last 2 years. There's several links just in this comment section that backs that up.

"Assault weapon" is a political term with no solid definition. If you mean banning semi-automatic guns, that's at least a meaningful proposal. Again though- this class of weapons have been around and readily accessible for over 100 years. Mass shootings are a modern problem. Why would banning them now be the answer?

Until the Orlando shooting, the VT shooting, committed with two handguns and 10 round magazines, was the deadliest in US history. Charles Whitman killed 14 people with a bolt action rifle from the UT bell tower. I'm not saying these disprove your assault weapons ban solution, but it's certainly not as straightforward as you're making it out to be.