This is an M4A1 colored in the "Tan" or "Desert" color. I just retextured the original m4a1 but i did it in a way so it looks like a counter terrorist disassembled it and spray painted it. The lower and upper reciever are painted, the stock is painted, the handle is painted, but the barrel and some smaller bits like the safety or takedown pin are not.
You could have overlayed the base textures if you want basic details to be left behind after recoloring it to a tan color.
You should have used the color balance function if some parts are not properly aligned with the current temperature of the color.
You can use painted shadows by creating a new layer above them, paint the shadows you want with black color, then decrease the opacity, let's say, maybe 20% or less.
I did see that you left the detachable parts un-colored since it looks good, but it doesn't fit actually. Just a personal preference though. If you could really brush the original details, then I will prefer this.