Look at a map and you can see how every river follows a meandering path covering miles and miles, at no point in a truly straight line. That’s because water follows the path of least resistance. Throw up a barrier and it goes around it. Even dams, structures we think of as holding water back, only do so because there’s a mechanism to keep the water flowing. If not for that, it would eventually find a new path, either over or around the dam.
For criminals, the path to obtaining guns is little different.
You see, anti-gun voices will often decry the lack of gun control in other places, citing those places as somehow responsible for their own violence. Take the city of Chicago. They routinely blame Indiana for their own gun violence because they trace guns taken from criminals and find a large number are purchased in Indiana.