Ah you mean there between the stock and the main chamber?
I guess I've been influenced from one of the testers at work too much haha.
He fixates on anything that's not 'uber realistic'.
I think I did try to tell him about those art principles in fact.
Most of your points make sense and I agree.
Still, no need for excessive amounts of dirt.
P.S: Modern, well-equipped forces->even terrorists (you could argue well equipped) and rebels keep their weapons clean. the gun is your life.