One of the reasons that Switzerland, a country te size of Bay Area, with 9M current population, has not been overrun by the many wars in Europe for last 200 years is that every citizen is expected to fight back, without formally joining a military force for that. All men have to serve in the military for a couple of months to get the basic training, obtain and master a small arms weapon, and keep it where they live. (The ammo is not provided though.) Every few years the citizens should show up for several weeks of refresher training.
This is very close to the idea that an armed population is a backstop against tyranny, but much better implemented.
Per-capita firearm-related deaths in Switzerland are 7 times lower than in the US, and firearm-related homicide rate, 20 times lower. Truth be told, firearm ownership per capita is still about 4 times lower in Switzerland.
Maybe they also are doing something more right with mentally ill people, who in the US often receive little help.