the vast majority of gun deaths are from handguns, not ar15s (or long rifles of any kind).
the difference in ar15s is range. and that only matters to pols who know they are pissing off their constituents.
best defense from an ar15 is moving serpentine after hoping they missed the first shot.
Restrictions on AR 15’s would reduce deaths in mass shootings including school shootings.
Other types of shootings might require other solutions.