   Aim down the sight systems
  How are Aim down the sight systems implemented? Does the weapon have to be modeled so that the sight is very good? In games like counter strike the sight look as if they can't be used in a Aim down the sight system.   
  If iron sights are what you're talking about, then all you have to do is make sure your weapon viewmodel is created properly, then make sure your code can put the model at the correct position on-screen when you want to aim.   ;  Modern games all use 3D sights now. A few years back though games used to switch to a 2D sight when you went to the ironsights view. Americas Army used to do that but now I think they've switched all weapons over to 3D. There was a point where half the weapons were 3D and the other half were 2D.   