I think that it must be clear to anyone watching the News that too many US deaths are caused by too many irresponsible people being allowed to hold firearms willy nilly.
When children can access guns in the cupboard at home, or in their mother's handbags, for example, then that is surely wrong.
This is how their friends, family, classmates, etc, can die deliberately or accidentally. I cannot see why anyone would argue against much tighter gun control.
I don't think that the history of the current situation really matters. Criticising American use of guns, etc, against slaves or native Americans, is no more anti-American than it is anti-British (and Irish) since so many early Americans were from the British Isles, anyway.