Missed this. I am not feeling some of the scratches on this. I think the ones around the edges, where the gun may hit a surface are nice, but the ones in the middle of surfaces seem to evenly distributed. Other than that looks great!
A few things I see on those pictures you posted can help sell the "plastic" more: -Most important: wear off the surface "texture" (tactile texture, as in the noise in your normalmap) on spots that will see more wear, like corners. Also change the diffuse color, the spec (stronger) and the gloss (sharper). You can tell on…