If you exclude the US inner cities, the US rate of gun homicides would be similar to Canada's.
The US has a violence problem, not a gun problem. The violence problem is the result of a disenfranchised inner-city minority with no resources, no jobs, poor education, a poor social safety net. In sum, no hope. Neo-liberal corporatism is making it worse, concentrating wealth into the hands of the few, reducing what is available for social stability.
If anybody believes in the trickle-down economy, advocated by Ronald Reagan, it means that the fire-hose of profit is pointed up towards to the corporate elite, while the droplets are trickling down to the 99%. The trickle down economy is the very definition of concentration of wealth. That is the cause of violence in the US, not guns.
In fact, there will be a time when a revolution will take place against a government totally subservient to the corporate and banking elite, that the 300 million guns in the US will help to rectify. The US founding fathers envisaged the 2nd amendment as a tool of popular revolt, and a safeguard to overthrow the tyranny of a government subverted by a foreign power (the British in 1776). Little did they realise that the 2nd amendment will be the tool to overthrow corporate domination from within.
Corporate control of government and its politicians is the definition of fascism. Their media then glorifies the military so they can facilitate recruiting willing participants who will engage in the subjugation of foreign countries into turning over their resources to them at a very cheap price.