Yes it looks like a split washer. I tried putting that washer in my vise, but I couldn't get a good enough grip w the soft jaws so I gave up.
Also, there is a pin and I tried to push it with a punch, but I didn't pound on it with the hemmer either. Felt solid....I will call CZ as I don't want to make more damage.
Would like to get some ideas on polishing up the inside "tube" on the bolt where the firing pin rides....that might help some.