It's been a bit since I read it, but I first saw the rule written down in Jeff Cooper's "Principles Of Personal Defense". The explaination I remember is that rewording it from "Every gun is always loaded" to "Treat every gun as though it were loaded" makes the statement much less concrete. It makes it as though it's okay to ignore the rule, because it's
as though it's loaded, rather than just loaded.
By stating it in this way, the idea is that the rule retains its importance and is less likely to be violated.
There are some additional advantages I can think of, as well (Cooper may have mentioned them, I don't remember):
If someone points a gun at me (or another innocent person), I have the choice of assuming it's loaded, or unloaded. This choice determines my next action. If I assume it's loaded, I can respond as though it's loaded, as appropriate to the situation. If I was wrong, and it was unloaded, I have still survived the situation. If I assume it's unloaded, and respond as though it's unloaded, but I'm wrong... Well, that's one time I really don't want to be wrong. In the interests of survival, it's in my best interest to assume it's loaded.
If I'm holding a gun, I can assume it's loaded or it's unloaded. If I assume it's loaded, I'm definitely not going to go pointing it at my dog and pull the trigger. If I was wrong, then the dog is safe, either way. On the other hand, if I assume it's unloaded, then it would be "safe" to point and pull the trigger. If I was wrong this time, then there are a few messes to clean up. Again, in the interests of survival (both from the angry dog, the angry housemate(s) and the angry law), assuming it's loaded is in my best interest.
I'm sure you all knew that, but I think that spelling it all out makes it easier to understand why every gun is always loaded.
Now, we're all thinking, rational human beings (or, at least I hope we are
). We all realize that there
must be some exceptions to this rule. And there are, but they're more of footnotes than bold, 60 point text. The exceptions are:
1. the firearm is rendered unable to fire. This may be because the action is open (signalled with a flag or a pencil, or whatever), or because the firearm is disassembled and the chamber is/are visible. The firearm remains safe until its condition changes, or its condition leaves the attention of the handler.
2. the firearm was just checked visually, and confirmed by sticking a finger in each chamber, and any ammunition that was loaded was carefully confirmed to be inert (i.e. snap caps). Again, the firearm remains safe until its condition changes, or its condition leaves the attention of the handler(this includes getting distracted by the television
but not dropping the gun)
Of course, everyone already knows all that *grin*