Well, this post hurts my pride, and was something I hoped to never have to post about.
At approximately 2140EST on 06DEC08, as I was clearing my normal carry sidearm (a Taurus Millenium Pro in .45ACP) in preparation for cleaning it, it discharged, sending one round of .45ACP JHP through one interior wall and 2X4 and through the exterior wall and siding, exiting the structure.
I KNOW I kept my finger off the trigger. Without a doubt in my head, I did- I'm very good about that.
Since day one this weapon has had extractor issues. It will extract a snapcap without problem. However a loaded round of 45, no matter the make, will hang up on extraction every time. The extractor won't even fit the rim of the cartridge well enough to hold the round in place with the slide off the weapon.
What I SUSPECT happened:
I dropped the mag, racked the slide, and failed to confirm extraction/ejection. dropped the slide and either had a slamfire, or put my finger on the trigger.
-drop the mag and put it away.
-rack the slide, observe the chamber, and account for the chambered round. I normally do this to the point of being OCD about it.
-BE OCD about it. EVERY time.
-NO, I am NOT "Good enough" to do this without ammo anywhere in the room
Weapon is going back to the manufacturer for a full going over, and the extractor WILL be right this time.
So in review, the problem was a combination of mechanical failure and wetware complacency.
As well, I failed at least 1 of the 4 Laws:
2. Never let the muzzle of a firearm point at anything you are not willing to destroy
On examining the entry and exit holes in the exterior wall, I find that I was about 10 degrees on the lucky side of going through an apartment building about 75 yards from my house. While possible the heavy and slow 45ACP hollowpoint would have struck the siding and embedded itself in it while doing no further damage, it's not something I would want to risk.
I got VERY lucky. This can NOT happen again.
I shook, hard, for three hours after the event, keeping my ears pricked up for sirens and the like. Heard nothing, have kept an eye on the news, and noone's been hurt. Yes, I would have owned up to it had someone been.