Banning semi-automatic firearms would do nothing except take them out of the hands of law abiding citizens all while criminals will still have them. The gun the Monterey park shooter used was a 9mm Mac 10 clone which is considered an SBR which is illegal on the federal level. He also has a suppressor and a high capacity magazine which are already banned in California. Theoretically, if semi-automatic firearms were banned, it would be safe to assume he would have still had one considering the fact he already had an illegal SBR, illegal magazines, and an illegal suppressor.

Firearm bans and firearm restrictions do not work and only take them out of the hands of people willing to obey the law. Or in other words, the people who would be trustworthy to own those things. Criminals will still always break the law to get or do what they want.

I think the best way to prevent shootings is to make firearms easier to obtain and carry for citizens. If at least one citizen had his own firearm in that dance studio he possibly could have stopped the shooter before he killed anybody. Just like Elisjsha Dicken did in that Indiana mall.