The shells in the blood in this picture look too clean. Wouldn’t that much blood pouring out of his head make them look bloodier?
It appears that the shells landed on top of the blood.
Well, the room was supposed to be carpeted, so it seems reasonable the blood could/should simply seep underneath.
But you're right, that's another oddity: the cleanliness of the brass — a lot of the shells look like unfired casings. (Too shiny, not enough discoloration, especially at the neck.) Though I will admit that could be an artifact of the picture quality in this case.