ND's happen to trained people, as well as untrained. With just about as much frequency? One police chief, has shot himself twice in his 20 years of police service, on duty.
Just what exactly causes ND's for trained individuals? One of you said, stupidity? Another said, failure to adhere to basic firearms safety rules.
The reasons go beyond what might be expected. Ever shout at your spouse? Ever almost kick your dog? Being tired, stressed, over worked, angry, depressed, anxious, worried, fearful, can bring on lapses in good judgment. Make a person do things they might not do otherwise. These stresses can also cause people to overlook things, not just purposefully violate good judgment.
One of the most respected firearms trainers of all time is Hickok45. He has a huge you tube following. He has a video, showing how to clean a Glock, where he unloads the gun, and leaves the loaded magazine on the cleaning bench. Is that good judgment? Is that correct procedure? Everyone has lapses in judgment, unknowing, or knowing, thinking they are good enough, to let it slide, no harm will come.
What is something you and I can do today, that almost 100% assures, we will never have an ND while carrying a handgun? This may differ, depending on what gun you carry. Some guns, it is easier to ND than others.
It boils down to two simple things:
READ THE HANDGUN OWNERS MANUAL, UNDERSTAND IT, AND FOLLOW THE USE OF THE GUN, TO THE LETTER.
Glock, Beretta, Sig, no matter, read the owners manual, and follow what it says.
Follow handgun safety rules. Basic handgun safety rules are usually taught as 4 rules, or 3 rules by the NRA
If you had to pick one set of rules, for someone with stress, family, responsibilities, deadlines, two or three jobs, and all the contributing factors that lead well trained people to slip and become the statistic of another ND, which one is the safest, and simplest set of rules?
NRA adds these rules, to their basic 3
http://training.nra.org/nra-gun-safety-rules.aspx