Two stories.
I normally don't report people who break laws unless the act is egregious, or ruins things for others. These kids came into the range with an AR that fired shotgun shells. You can only fire single projectile ammo at my range, and these idiots were firing buckshot into the targets and wood absolutely destroying them in short order. Made a call to a buddy whose a Warden and took care of those guys in short order. Was extremely satisfying.
The second, made me stop going to the range for over a year.
I was up there, just me, another guy next to me, and two more further down the range. Guy next to me calls clear and all the others go down and change targets. They come back, I check downrange to see if anyone is still down there, don't see anyone and prepare to fire.
As I flick off the safe and begin to aim, the guy next to me yells YO WHAT THE HELL ARE YOU DOING?!
and points to someone still being downrange. I looked again, and only after carefully looking there's still a guy down there at 100 yards. His clothes, jacket pants and hat blended perfectly with the range backstop. I just never saw him, and further it was a tremendous lapse of judgement to not at least yell going hot to the others to be sure. This was the first and only incident I've ever had of something like this happening, and it screwed me up bad. I thank God that guy next to me said something. The guy downrange wouldn't have been hit if I had fired, but I couldn't imagine how mad id be if someone had fired while I was downrange. I literally stopped going to public ranges for well over a year after that it shook me up so bad.