I try to be safety conscience any time I am around a gun, but screwed up big time yesterday and had an AD in my shop. I had just replaced the hammer spring on a Smith model 60 for a friend, I checked the gun out before putting it back in his holster and laying it on a table. It was unloaded, and the five rounds of .357 were laying next to the gun. I called the friend and told him his gun was ready, he showed up a short time later, took the gun out of the holster, checked to see if it was loaded, and dry fired it a couple of times, he then returned the gun to it's holster. As we talked he made a comment about smoothing the action out a bit, I picked it up, pulled the hammer back and squeezed the trigger, BAM. I didn't notice him reload the gun after he had checked it out. I almost lost a finger on my left hand, shot a hole in a beautiful picture hanging on the wall, and put a nice hole clean through both walls. The bullets flight took it out into a lake area where there are not normally very many people.
This serves as a refresher course for me, from this day forward I will make it a practice that no one brings a loaded gun into my shop, nor do they load one while there. It has also got my attention and now I will check every gun when I pick it up, makes no difference what the circumstances are. I consider myself and friend to be very lucky.