The data are high variance, so you can't just pick individual cases and then only look at selected facets of them. That's classic cherry picking.

You've got to look at large scale trends if you want to see a large scale pattern, and, if you want to dig into the particulars, you need to look at all the particulars. For example, that article you cite fails to consider the different levels of organized crime between the two countries. Perhaps because including that detail might necessitate acknowledging that Brazil and the USA have different gun crime problems with different causes that might therefore require different responses.

"Go compare the gun violence rates in the US with any country that actually regulates guns."

Given that the first sentence mentioned developed nations I figured it was clear I meant any developed nation. Furthermore, regulates guns generally means actually regulates guns and not "has laws for regulating guns." The two are not the same except in countries that have stable governments, enough money to pay for law enforcement and low amounts of corruption. Unless you actually believe the state of the US government and economy is akin to that of a country like Brazil?

Brazil has the world's 9th largest GDP. Does this look like an undeveloped country:

https://en.wikipedia.org/wiki/S%C3%A3o_Paulo

Depends if you live in this part of Sao Paulo or not:

https://en.wikipedia.org/wiki/Favela

Brazil is around the 80th in terms of per capita GDP which is a much saner metric for the wealth of a country in terms of social issues.