The Minority Marksman.
"When you meet a swordsman, draw your sword: Do not recite poetry to one who is not a poet."
-a Ch'an Buddhist axiom.
The worse thing about the mentality is the fact the car gun people are often the same ones with firearms related bumper stickers...
My opinion, maybe all manufacturer should have printed on the case of each firearm. "As a responsible citizen, it is your responsibility to keep it from unauthorized people". This will drive the point home maybe. What I often see, if people look at the secure device in the case and look at it like "Why or what is that", they have no idea that there is a U.S. code, stating "All new firearms must come with a device to secure it from unauthorized people".
Didn't read the whole thread so I hope I'm not repeating anybody. This thread was linked from another one I did read about a fatal ND that occurred while two dumbasses were cleaning guns: https://pistol-forum.com/showthread.php?44864-Unbelievable-dumb-cleaning-mistake-kills-friend
If I were going to add a fifth rule it would be:
Dropping the slide with a loaded mag loads a round.
I don't ever recall hearing people talk about this in terms of safety before.
The DEA agent that shot himself in the foot in front of a bunch of kids did the same thing.
"Freedom is never more than one generation away from extinction. It has to be fought for and defended by each generation." - Ronald Reagan
It's specific to mag fed semi autos so not a universal rule.
Plus it's not that simple. The Ex-NFL DEA guy did not know he had a loaded mag.
He racked a round out and locked the slide open but never dropped the mag. In the full video he walks over to the other black DEA guy against the wall, shows him the open ejection port with the brass clearly visible and says "clear ?" Wall Dude had the chance to save his buddy but instead he looked without actually seeing and repeated "clear." NFL dude then dropped the slide on what he thought was a twice verified clear gun.
He thought it was empty because he saw a round come out and assumed slide locked back = no mag.
The whole "5th rule" thing always devolves into a shit show of semantics and assholes who think they are always the smartest guy in the room as with the recent thread you linked.
When clearing for anything, for a long time now, I've been into the habit of looking three times. Once, you're not really going to look if you look a lot. Twice, you can half-ass. Three times requires some deliberation. That dude was into the habit of "I put my eyes here, and then I say 'clear'". Similarly, I detest trying to rush shooting relays because that's exactly how you develop shit habits like that.
I never did that until my current employer taught it that way in the academy. Visual inspection and physical inspection, even running a finger around the chambers of a revolver. I initially thought it was overkill but came to appreciate the extra layer as I got into low light training and got used to it. There's no "digital exam" for ARs, but we use chamber flags/ropes there, so the gun isn't in a functional firearm at that point.
Sorta around sometimes for some of your shitty mod needs.
I like to incorporate touch, but on a bunch of guns I own/deal with, it's just not feasible--various match .22s, for instance, just don't have the clearance even for my skinny fingers. At matches they get chamber flags, at home they're visually checked and then dry-fired into a wall.
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Now that you're done cringing, my pistol has a non-interference chamber--i.e., the firing pin couldn't strike the chamber face if it wanted to. It's not long enough. It's a popular feature on fancy-ish BE guns due to frequent dry-firing practice.