yet everyone has AR-15s because Gavin Newson

The issue is significantly more complicated than that. The U.S.'s laws on guns are incredibly fractured. Some guns are legal in some states, some protections exist in some states where they don't in others, etc. So the result is that the supply of AR-15s in a state where they are banned is still a high supply because the surrounding states do not have the same protections. Plus on top of that, the U.S. has intentionally destabilized latin american countries and started a drug war, which further drives the black market for these weapons.

And this is why we need these protections at a federal level, ideally through a constitutional amendment to prevent the protections from getting chipped away bit by bit, and to keep the law consistent across states.

It also wouldn't hurt if we could stop toppling foreign countries and fueling the profits of cartels through the drug war.

> Gavin Newson can’t properly define what an assault rifle.

It seems pretty straight forwardly defined to me. "California law currently bans certain assault weapons by specific type, series, and model and also by the firearm’s general characteristics"

https://www.oag.ca.gov/ogvp/fed-assault-weapons-ban

> What does he hope to accomplish with this?

I'm not Gavin Newson, so I can't speak to his motivations. But ideally we would join the rest of the developed world that does not experience school shootings on a routine basis. The U.S. is unique in this problem, and we can absolutely solve it if people cared enough to vote to end children getting shot in schools.