The alternative is to restrict access to concealable firearms, and going anywhere near this is politically unviable. Gun policy is used as a political football (so it doesn't even matter if more than 50% of Republican voters support better regulation), it leads us back here. That being said, as far as school shootings by teenagers are concerned, restriction of concealed arms probably works: it matters not that criminals don't acquire their guns legally, teenage shooters aren't career criminals, they just use their dad's gun, or in this case, buy it legally. And unless gun control translates to "asshole dad doesn't have a handgun", it won't mean anything. Gun advocates are leery that concessions would lead the conversation next to bans, probably correctly.
If you want change as soon as possible, take the first path. Otherwise, change the fabric of politics in America. Get rid of the PACs and SuperPACs.