Yes it was the small wire ring around the end, it bent up and got jammed in the cocking mechanism thus jamming it. I will take a photo of the part I have that fell out, and I did the same thing, except the part fell out before I even got the plastic housing off.

I have the Compact CP99, and when I was disassembling it a part came out and I have not been able to figure out where it went. I had an issue with the metal ring around the back of the part in the third and fourth photo you posted, it jammed and would not let the gun cock, so I had to tear it down, ...