This is another reason I'm glad I left NZ. I did have one friend who had guns; but they were really expensive to purchase and license. I think our gun laws are the reason much of American avoided lockdown tyranny, not with the guns themselves, but the general mentality that comes from a nation that possesses them.
As far as American mass shootings, the thing no one talks about the insane amount of drugs we prescribe. SSRIs are shown again and again to be useless after the initial acute effective they have, and yet they keep being prescribed. We have more and more kids on Adderall, SSRIs, Ritlin and now, cross sex hormones. Messing with peoples' brains is incredibly dangerous. Everyone well known mass shooter was on some combination of clinical drugs.
There is also the fact that at least some of our mass murders were directed or facilitated by the CIA. Oklahoma City and the life of Charles Manson are great examples (Manson's psychologist at one point was literally an MKUltra doctor). These events will keep happening because our leaders need to disarm the population, or else they'll never get the Chinese system they envy so much.