Never mind that this runs contrary to state law and that the city lacks the authority to do so. As the Clam says,
Problem: they tried this in the 1980s, when Feinstein was mayor. It didn’t work then, because the California Court of Appeal ruled that state firearms regulations preempt such local regulations, and localities lack the power to ban guns. Likewise, when West Hollywood tried to ban “Saturday Night Specials,” a different district of the Court of Appeal rejected the law as preempted by state law.