Most of you guys know the story but here's the details with video evidence.....
First off––-this is a used gun. Upon receiving it, I inspected it (all pins in the right place, ect...) followed by a proper cleaning and lubrication.
I was out at the range and put about 5 magazines through the gun when the firing pin broke. Yup, broke––-in half.
I didn't realize it at first and thought I had somehow hit the slide lock since I knew there were still rounds in the magazine and the slide had 'locked' to the rear. Only it hadn't locked. I could still pull it to the rear slightly. Upon further inspection I saw the firing pin block sticking out of the slide and it appeared the firing pin was missing (it was actually broken as mentioned earlier).
Here's a photo of the firing pin:
Here's the video of it happening and a close up of all the internals of the slide (including the firing pin):