“I am more and more convinced that the core aspect of the anti-gun crowd’s motivation is their awareness of their personal irresponsibility and knowledge that they are unsafe around firearms, and their misapprehension that because they are unsafe, so is everyone.”
The term you’re looking for is “projection.”
I don’t think this is a case of actual projection. Projection is where the projector refuses to accept the feelings/actions they’re experiencing, and transfers them to an “acceptable target”. I think in this case, they realize on some level their own untrustworthiness, and commit the fallacy of believing that everyone else is the same e.g. the “False Consensus” fallacy. I believe there is also a related cognitive limitation that children experience e.g. egocentrism, which has the same general parameters. This childlike belief would also tie into the notion that Leftists are emotionally/developmentally stunted in some fundamental way.