I actually posted this last night around 4:00 AM, but got embarrassed, and deleted it.
My dad got me shooting around the age of 6, and I'm 61 now. Never had a negligent discharge until a couple years ago. Totally my fault/stupidity.
Was watching TV in my living room, and thought I'd strip down, and clean and oil a newish AR bolt I had in a 7.5" 5.56 SBR AR.
I put 5 rounds in a mag and ejected them to make sure everything was cool, which I knew it would be. I was sitting in the floor working on it, with a mat laying on the laminate flooring.
Laid the AR on the floor, and went to put the mat up. Came back to pick the AR up off the floor, and in the process I tapped the trigger. SURPRISE SURPRISE SURPRISE! "in my best Gomer Pyle impression." There was a magic 6th round in it.
Bullet made it half way under the couch which only sits 3 1/2" off the floor before coming in contact with the floor, then ricocheted up about 4" and went thru the wall. How it didn't touch the couch is still a mystery. I held my breath while I opened the front door to see if it exited the block wall. It didn't.
The damage is about a foot or so from a little tile foyer, and I have a half box of unused laminate, so I can fix it if I ever decide to move the couch.
The gash is around 7" long. AR's are monster loud outside with a 16" barrel. I hope none of you ever hear one inside thru a 7.5" barrel!