I handle guns all the time and sometimes find my attitude becoming a little overly-familiar. Since I know that familiarity breeds contempt, I periodically take a look at the sign above my working desk and reflect on the wisdom thereon.
The first line: "All guns are always loaded" Note that it is not "treat all guns as though they were loaded." but rather a positive declaration that says in effect, "if it's a gun, it's loaded."
This was a principle first stated by Col. Cooper, who was sufficiently skilled with the language as to require no editing from latter day hotshots.
If you accept what he said, there is no excuse or argument for any form of negligent discharge. And if you don't get the subtlety of his phrasing, you need to stay away from firearms.