Wow this looks pretty good, you made this yourself? One critique I would have is definitely the sight picture is too wide and unrealistic, you should tighten that up a bit to be more true to reality. Another thing is a lot of your normals have artifacts on them, the bake on those could definitely be improved especially on again the sight picture (this is very important because it's what the players will be looking at most of the time).
Overall it's good, I'm certainly fairly impressed, and we need a Pzb39 so this could be a perfect fit.
Really nice work! adding to PotatoLord's points about the sights, I think you can make the edges a bit more smooth and waste some more polys there. We don't really want sharp edges on the sights (which will be in player's face most of the time). Plus, I'd make the sight UVs a bit bigger, so that screw normal map would be less pixelated.
Other than that I feel like it's really good! well done.
If you are happy for us to integrate it into the mod, could you upload the files somewhere, then we can also store on out asset repo.
Looks very good to me so far, I can give you any further feedback on reviewing the mesh/uvs. It may take us some time to finish due to its animation complexities but otherwise would be a great addition to the mod.
We have plenty more stuff we are looking for if you are interested in any other assets