Okay let me start hating. Well its all honest but this model is really bad, especially for a developer. I know you don't like me and I know that I don't like you but this is an opinion on the model, not entirely towards you.
First of all, you're investing faces in the wrong sections. You apply around 30 faces just for the rubber things the gun is on, while you invest 4 on the bad ass point of the barret. The point of the barret is in my opinion one of the few key factors you'd see in-game and is also what makes the barret the barret.
Now the center of the gun is just an extruded box (you can see this good in the last screenshot). Also the trigger is boxy as hell and the handle as well. Now the handle and the trigger party okay, you'll barely see them but its still pretty ugly.
The scope has to many cylinders, this is investing faces in the wrong parts AGAIN. This can easily be textured as well.
The shoulder parts looks really messed up, I don't know what you did with your geometry there but it has a bad flow.
It looks like you made this model with basic objects only, you made boxes and cylinders and extruded and scaled some parts, try to have better edgeflows in your models because box modeling doesn't work for games. Actually it works for barely nothing, could only think of render environment. Anyways that doesn't matter
The way you texture your gun is also pretty hilarious, you give everything a plain color and dodge/burn or add shadows, this isn't texturing. It looks really amateur the way you textured it.
Overall I would give this model 1 out of 10 points for the effort you put it in it, please don't be stupid and learn from my advice. Again, this is one of the reason I don't understand you got this position, 600 faces for a box model weapon? Should be 200.
Please remove yourself from this discussion, you have 0 knowledge about development. All you can do is look at something and say if you like it or not. The model isn't usable for gunz, a moron like you might understand it if we say it this way.