Hey so i have made a gun in blender and just out of curiosity what would be a good amount of polys? It has 2,5k but i think that is too much so what would be the best balance between performance and quality, and what do you guys go for? And how does smooth shading affect the performance in unity?
Hope someone can help 
Hard to tell exact number, depends on type of weapon and context it’s used in. For third person and prop guns that enemy characters are supposed to use, not much. However, FPS weapons in modern AAA games are pretty detailed because they are always in view and taking up significant portion of screen.
You might want to check this thread on polycount - there are no wireframe shots but lots of high res images. As you can see fps weapons can pass close inspection test pretty well.
Thx for the reply, so in the comments he says that the weapons had to be between 1500 and 3000 polys so if i consider the fact that the game was made 3 years ago and the engine is pretty old. Would the main character weapons in my game have to be 2000 - 3500 or 2500 - 4000?
2500-4000 polys does not sound unreasonable at all. But again, your assets do not have to be anything. Depending on target platform and specifics of your game, you have X amount of triangles you can afford on screen at any given time and you allocate them as you see fit. You need profiling of some sorts to determine this.
If you are artist making something for portfolio or study, just make it look good and use common sense for optimizing geo. Do not butcher content just to hit some arbitrary number and do not model tiny screws that can be baked down to texture easily.
Ok, it’s not for school or portfolio it’s just my first model that i made in blender for fun :). And i guess that with building and other models that i just will have to experiment?
Forget polycount. Just make stuff. Make it look good. For a long time I was putting the preverbal horse before the cart when I started worrying about optimization. But the thing is, there won’t be anything to optimize if you don’t create it first. As you do more and make more things, you will start gaining an understanding about these kind of things and you won’t have to ask, because you will realize quickly that you are the only person that can answer that question for the type and target of the game you want to make.
Beyond that, you can use the high-poly version of the model to make a very nice low-poly version by retopologizing it. It’s a common workflow.
Thank You, will remember that 