There are no countries with comparable gun ownership, and ease to obtain one at a supermarket. Nor where assault rifles are available to everyone. Nor I know any Constitution with a provision like the second amendment, and no will to change it after a quarter of a millennium.
The cultural problem is exactly this.
There are countries IIRC like Switzerland where able men after military training keep rifles, but they are also bound to attend more training at regular intervals, far easier, in a small country, to spot troubled ones. And a very different, and richer, society, anyway. So, hardly comparable.