With the new addition of messes and bloody messes, I almost immediately got this idea forming in my head.
The title is pretty self explanatory; piles of spent shells could build up around where there have been gunfights. Those with the right tools and knowhow could ID the type of round, and those interested in covering their tracks could spend an extra while cleaning up their blood and bullet casings (or pay someone to do it for them, opening up a potential new criminal enterprise :D)
Thoughts on this? I imagine there could be other little additions made to the mess system overall, clothing tatters, stuff like that. But this one immediately comes to mind