Shooting Star
I’m not sure why someone would want to shoot a gun in space in the first place. Maybe to defeat some evil alien overlords? Either way, there are many different reasons why this isn’t a good idea. Of course, there is no sound in most of outer space because it’s a vacuum.
However, there are some places where you’d be able to hear a gun if you fired it. According to NASA, certain galaxy clusters have a lot of gas that sound can travel through. So that’s the place to go if you want to hear a gun fire, for whatever reason you desire!