Violence and gun control: South America and Switzerland

From the Forbes article We Have A Lot Of Guns:

... it is not surprising that where there are more guns, there tends to be more gun-related deaths, but northern Latin America (Brazil in particular) breaks from this trend in a major way. The area has a massive homicide by firearm rate, with some of the lowest rates of gun ownership in the world and the highest homicides by firearm count. This suggests a lot of guns in the hands of very few, who are not afraid to use them. Talk about data telling a story…

That northern block of Brazil, Colombia, Venezuela and Ecuador combine for more homicides by firearm than Mexico, the United States, South Africa, the Philippines, Honduras, Guatemala, India, El Salvador, Dominican Republic, Bangladesh, Argentina and Jamaica put together. That is every other country with over 1,000 homicides by firearm. You would imagine that gun control would be very lax in the area, but as the top chart here illustrates, that is not the case. Brazil, for example, has roughly 255 million fewer guns (and about 115 million fewer people) than the United States and a much more strict and effective set of firearm regulations. So, while it is true that where there are guns, there is gun violence, that is clearly not the only determining factor.

There's also Switzerland, which has one of the world's highest rates of gun ownership and, simultaneously, one of the world's lowest homicide rates (full list of countries here). Of course, Switzerland does impose mandatory military service upon its male citizens which means a high level of firearms training.

You have some studies like this one arguing that gun control increases crime, and other studies like this one arguing that the opposite is the case.

What's the best answer...