It's not easy to spot, especially if you already dissected the gun. That's probably how it got past inspections in the first place.

Oh yea, it can be fixed easily. If you still want to practice with this though, I'm going to have to ask you to check out one that came from another manufacturing lot. They should be identical, Apart from the fact that they work, but I can't lend any of those ones out until I do a full inspection.