One of the arguments I see all the time is that "criminals are criminals, and they'll find a way to get guns no matter what". That's true to an extent of course. People in organized crime and such will obviously always be able to get access to guns, but those also aren't usually the people shooting up schools and churches and movie theaters a lot of the time. It seems like most of the time it's just some crazy person on their own who isn't going to have those connections to easily obtain illegal guns.
American's can root for guns all they want, but this shit isn't happening in any other first world country.