this is a solid work, wow!
I honestly dont have anything to add!
a bit late but if i'd give my lil critique on it, it would be about the lever and safety catch (idk what you call those, but those two things that stick out at the top and they move when you shoot) could add more worn effects to the sides of it, however, depends on how worn out you wanted to show it. (but ye, what do i know xD )
anyway, solid work, love the render of materials and especially this action part with the slight change of colour!