I think that mischaracterization comes from timing. Those in favor of gun regulation (or gun bans, etc) are always in favor of them. Those against them are always against them. But there’s this mass of people in the middle who could potentially be convinced. So every time there’s a massacre, people on both sides try to convince the people in the middle that their policies are best.

The pro-gun side sees this surge of effort from the anti-gun side after every massacre and thinks that the massacre caused the policy view, and it’s a gut response, but of course it’s not. The same thing could easily be said for the pro-gun side, who (usually much more successfully) relaxes gun laws every time there’s a massacre. You could say that’s a gut response too, but it’s not. It’s just pushing policies they’ve always believed, using timing for political leverage, that’s all.