Unusually, I'm replying to my own post, but I actively was an NRA certified instructor up until a few years ago. You would not believe the scary stuff that happened and the close calls.
I had one student somehow load his gun, a 10 mm Delta elite, and put around into the floor in the waiting area of the range. I had a police officer load his Glock, drop the slide and pull the trigger in the showroom sending a round pass the cash register and into a wall of ammunition. I had one woman turn around with a cocked charter arms 38, and whiz a bullet passed me and into the wall behind the shooting lanes. One police officer severed his middle finger when his Glock fired as he was trying to put it into its case loaded. He actually got it into the case, and the pistol fired when he attempted to snap on the lid. Another pulled the trigger as he was holstering his weapon (Glock) and shot himself in the calf. Yet another police officer managed to get his loaded Glock into its case, put the case in the trunk of his marked police cruiser, only to have it fire when he slammed the trunk closed. That bullet hit him in the extreme upper thigh about an inch away from his privates (and luckily his femoral artery as well). One intentional suicide with a 41 magnum, whereby bits of the guys skull went through the drop ceiling at the shooting lanes. There were several other suicides, but I did not directly observe them. One guy with a trophy blonde was waiting outside the classroom in his red convertable 'vette and put a 45 slug into or through the transmission. He was actually able to drive it away for some distance! I ran out the classroom door to see a stacked blonde giving him the what for, and him getting the car into reverse and then drive, as he puked fluid down the road. I think he made it to the 2nd crossroad about 1/2 mile away.
Those are the kinds of people and guns that scare me the most.
(later edit....)
>>>> PUBLIC SERVICE ANNOUNCEMENT <<<<<
I replied to myself because my brain wouldn't let the fear factor go. A few things that I've taken away from all my experience. First is the arrogance of some shooters, supposedly "trained" shooters, professional Lawmen mostly. Emphasis on "some". Dad, rest his soul, was Detective Sgt. and he pretty much wanted nothing to do with his revolver, a S&W 36. He had a model 10 too from his patrolman days. Never ever shot 'em, except as mandated by his department (Suffolk County PD, LINY). No arrogance there. So not saying all cops are that way, just some.
Second take away is the outrageously stupid and dangerous design of the original Glock case, with the post in the middle that was supposed to prevent the user from putting the firearm into the case loaded. A lot of folks tried. Some got shot and lost careers, at least one lost a finger and a career, and I'm sure there are instances of folks getting killed. For the love of all things Holy, please, please throw that case in the trash if you have one. Imagine you NOT getting shot, then a loved one touches the case, dislodges it on a shelf maybe, and BANG!. Forget the instructions, just forget the case forever, and toss it in the landfill by way of your trashcan.
Last, is the suicides. It got to the point that you could recognize certain mannerisms, talking points, physical (bodily) things about a person, and be tipped off to "better not". Nervousness, didn't seem to be one of the traits. Asking if they could just "try" a gun, did they have to buy a whole box of reloads or ammo, just one target, or no target. They only wanted to see what firing a gun was like. The raisin like skin some chemo patients have. Gaunt sunken eyes and cheeks. The ravage of cancer evident. Coming in at a "slow time". I feel for 'em, but please.... not in my range. I loved the job, think of the adventure for a man in his 20's and 30's. I hated parts of it, the parts I'll never shake.