Canada also has a health care system where mentally ill folks can get help.
Canada is also less population dense and only has roughly 1/10th of the US population.
Even though other methods of murder can be devised, restricting access to the easiest, fastest method is effective in reducing murder.
The per-capita rate while a useful tool is not going to compare the effects of mass shootings. You’re more than likely talking about handguns in this context which are responsible for a lot more deaths overall than AR-style rifles.
Switzerland has lots of guns but not mass shootings, and has a much lower murder rate. Finland similarly has lots of guns but not mass shootings.
The bigger issue is that half of the US government doesn’t want to fund mental health programs, red flag laws, etc. There are some models we could follow other than “ban guns” or “ban assault rifles” … but dealing with rampant mental health issues would help a lot. It’s just a shame the Republicans will parrot “mental health” but then not vote for bills that will actually do anything to improve mental health.