I don't think it is useless at all. The more guns are circulating in this country, the more likely that more will be used to shoot people here or perhaps exported to shoot people elsewhere.
Nearly all the illegal guns in Mexico have come from the US
Mexico has much more restrictive gun laws and a much smaller gun per capata rate.
But a pretty bad rate of violent crime .
Your central thesis here "The more guns are circulating in this country, the more likely that more will be used to shoot people.." has a problem in that it is very disconnected from practical experience.
If our gun laws were more restrictive , and our gun availability were more like Mexico, might our violence rates rise to México's level?
Probably not, there is a lot more going on than availability of guns to the public.
If it were impossible for guns to be sold south into Mexico out of the USA, but all else were the same , those narcotic smuggling gangs would still have no trouble at all getting plenty of guns. They are Millionaires , they can get guns from Belgium and China and Brazil
it is the common man in Mexico that suffers from the restriction that they have, and would suffer more if the restriction were tighter.