Not only have I seen guns at yard sales...
I've missed them at more than a few!
Here in Vermont, we see them at antique/flea markets all the time...
The unofficial GOLDEN RULES OF FLEA MARKET FIREARMS FINDS:
Rule #1
Don't EVER touch, until you ask: "May I handle that weapon? Is it loaded?"
Rule #2
Imediately open the action and check the chamber/magazine.
Rule #3
Follow the four golden rules of gun safety.
Rule #4
Make sure that the weapon returns safely to the spot from which it came or that it leans against your shoulder with the barrel pointed straight up until it gets home.
I've been present more than once during a stressful period of:
"HEY! watch where you point that thing, you idiot!"
Or seen people who will rest the muzzle of a weapon on their toes while looking at something else...
It's always the same dumb rhetoric:
"It's not loaded."
"IT'S ALWAYS LOADED, TREAT IT THAT WAY!" is what I always yell at them.
I usually get dirty looks from people for being so "anal"
"It is better to be safe than to be sorry." I always say...
Here's a little nugget for those of you who don't think that a standard safety routine is that important...
I ALWAYS rack the action a few times before I "lay down" a weapon when I go shooting at the range...
The other day I was firing some loose ammo that I had rolling around in the bottom of my range bag through the AK-47...
Apparently one was a dud...
I figured I had emptied the mag and on the "I thought" last trigger pull, heard a click and assumed I was done...
Keeping the weapon in the follow-through position I racked the action back and out pops a round that had a pronounced dent in the primer.
I aimed at the target and pulled the trigger and continued to fire 2 more rounds from the remainder of the 75 round drum...
The first thing I do is to remove my finger from the trigger.
Then I open the action and leave it that way.
Next I remove the magazine/apply the safety... if it has one...
Then and only then do I disengage the firing line...
"Safety works for the benefit of us all"
-Sign at a construction site