"That thing you're doing? Well, it's having a direct effect on me."
And they answer: "No, it's not."
And if the effect is question is the sending of bullets in my general direction, and they refuse to acknowledge that reality ... well, I'd probably call the authorities pretty quick. Gun safety should always be a top concern. It gives all gun owners a bad rep if some yahoo refuses to understand that.
You said it.
Don’t wait for a stray bullet to blow someone’s brain pan out to start thinking about escalating.
Either the guy is dangerous or incompetent. When you’re talking about the possibility of killing someone, you stop that person regardless.
The shooter in this case is obviously causing the problem, but sometimes with less obvious things determining fault can be problematic. An example from my life: my dad was a HAM operator. Dad took every precaution to avoid interfering with the neighbors, but one fellow insisted that dad's transmissions were coming through his TV. Nobody else, including plenty of folks the lived much closer ever had an issue. Dad spent a lot of time and effort trying to determine what the issue actually was, but since the angry neighbor wouldn't let him come into his house he was never quite sure. This went on for years. Then dad died. A while after he died, the neighbor was on the phone demanding to speak with him because he was coming through the TV again. The guy changed his tune when he found out that dad was gone and the contents of his radio shack had been sold. I never heard what the real source of the interference was. We'll probabaly never know.