It's looking good you've made some nice progress! 1) I'm not sure of the material the main part hanging under the barrel. You are being really conservative with reflections/roughness/glossiness, it looks like really dusty, greasy and undisturbed like it's been in the back of some grandpas shop and not touched in decades.…
It's getting better but you should re-read Bek's advice, the whole gun has too many areas of high frequency noise I highlighted them in the following image The rail at the top is far too noisy, as well as the bolts/slide on the side of the receiver. The forward grip is passable to be honest considering it's a grippy…