the linked wiki article refers to a small arms survey. this survey is based on manufacture and importation. It routinely states that it makes no distinction between illicit guns and legally purchased ones. So this is total guns.
You said that corpses are much easier to count. Why is the united states with less than 5% of the global population and between 35-50% of the worlds small arms not just full of bodies in the streets.
Your link supplies a higher percentage of deaths by firearm. I am not sure that this is a useful statistic clearly Thailand had a high percentage. I don't doubt that there is very high rate of homicide by firearm in these 2 country's. SA 74/100000 Thailand 33/100000 and the US 3.7/100000. Are there other factors that may be to blame besides the amount of guns? The US seems to have a much higher number of guns and not nearly the homicide by gun rate.
It's too bad that you live in a country with such oppressive firearm laws that you have to purchase on the street from corrupt police officers.
I think we could go back and forth forever. There doesn't seem to be good enough data to sway either of us.