When I teach any firearms class I always address manual safeties during the preliminary brief. I always emphasize, “Use the safety, but don’t rely on it! It can and will fail!” Gunsmiths make a living fixing broken mechanical devices, and the safety on your firearm is just a mechanical device like any other.
Here is an example that is in my shop right now. A customer came in upset because in his own words “I nearly blew a hole through my living room wall…” That’s why we treat every gun as if it were loaded, right? Disassembling the Mossberg 500, I discovered that a metal tail had broken off the trigger itself. Yessir, snapped right off. I place a red arrow pointing to the rusty spot where the tail usually resides:
This is a big deal because that metal tail goes through the piece I’m holding in my hands. The “Y” shaped piece is referred to as a safety connector. Its job is to point a piece of metal upwards in the receiver so the “L” shaped aluminum block underneath the safety can touch it when the safety is in the “safe” position. With the aluminum block holding the safety connector down, the safety connector holds the trigger down, you can’t pull the trigger, and the firearm is rendered safe. Unless, of course, one of these small pieces actually snaps off. Now the safety connector isn’t attached to the trigger anymore at all. Pull the trigger and the hammer falls, discharging this 12 gauge regardless of the safety’s position.
I want to point out that this situation isn’t Mossberg’s fault at all. See, while I was poking around in the guts of this shotgun, I noticed that the owner had installed an aftermarket AR-15 style stock using a bolt from a hardware store. A bolt that was just a bit too long. A bolt that hit the “Y” shaped safety connector and pushed it forward, snapping off the metal tail on the trigger as the stock was tightened down. I’ll bet most of you didn’t know that installing a tactical stock improperly could break the safety. And that’s why we follow the multiple, redundant, carefully thought out rules of firearms safety.