The hinge is S&W's version of a trigger safety. It can not be pulled unless both pieces are fully aligned. I carry a Sigma with the same setup. It's been trouble free from day one.
That's the one I was looking for. You can let the thread die now. I never meant to say there was anything wrong with it, or that it was fragile, it just looks that way and has an odd kind of shape/feel to it.
Try this again.... Can anyone explain the M&P trigger to me? It just seems really...odd. It's like that tiny fragile plastic part that breaks off anything you put any kind of force on. I really like the gun, that trigger setup is just very off-putting to me every time I pick one up.