My late brother, God rest his soul, and I would talk about gun control… he had the gunsplaining argument down pat. As you say, he would ask for my definition, and I would say everyone knows assault weapons when they see them, like an AR-15. He would then shoot (pun intended!), my definition apart. We never resolved this, but chose not to talk about it. Was he a toxic male? No, he was one the kindest and gentlest men I ever knew. Why was he not toxic, and many men are? This would be a good question to be looked into. The causes of toxic masculinity can be listed, but the solution is more elusive, especially now when toxic behaviour is encouraged from the highest office in our land. It’s when the two meet (toxic masculinity and bigotry) and combine with gun culture that killers are made.
I wish gun control would solve it… I think it is a good, necessary and easy (with the proper legislature!) first step. The bigotry is another matter… I feel the pool from which mass shooters come is relatively small (most alt right protests are smaller than the counter protesters), they are the ones who “boil over” for whatever reason. We need to find a way to lower the temperature. More open support (including electing to office) for women, including trans women, is necessary. Allies need to make themselves heard.
And, judging from some of your response, the truth that white males are the vast majority of mass shooters needs to be recognized, especially by non-toxic white males, who are in the best position to deal with this scourge. It seems to be clear as a bell to everyone else.