Agreed. The gases still escaping from the open end of the casing in back show it to be a fired round.
Wow, I hadn’t even noticed that or considered it. When I mentioned expelled gasses before I was referring to those escaping the barrel. Good catch! Of course there would be some in the casing as well.
The photograph itself is remarkable. Clearly taken with a very good camera using a high shutter speed IMO. The photographer him/her self is very skilled too. And still it’s a once in a lifetime shot. One brief moment before or after and none of the elements we see would have been there.