very good, although I like to point something out
I know that sounds annoying, it isn't about the model, which is in fact really detailed and accurate, only about the opmization.

In red, those holes on the handgrip can be perfectly made within the alpha channel on the diffuse texture like I made here

in yellow, even if you wanna keep it as geometry since it is closer to players view you can optimized by merging(or welding, in 3ds) all the vertex to the corners, not to the mid point or arbitrary points like you made.

in green, it doesn’t seems a big deal, but each piece highlighted is wasting 6 tris, due the bad triangulation, try to delete those edges and apply a automatic triangulation.

blue arrows, shows some edges that are completely useless, subdivisions are only welcome when make things rounder or add detail, in these cases you’re using subdivisions on a strait line, which doesn’t help at all.
At last, as Rhinos kindly posted here
https://www.realitymod.com/forum/f189-m ... nders.html
you can make the scope look much better by increasing tris only on the last subdivision closer to the player view.
These little things can save you a lot of tris, I would say 10-20%, not to mention some probably hidden faces, with little or no quality loss.
Maybe seems bullshit saying that 1000tris will boost performance, but if everyone think that way it will.