I was wondering how to make my gun, well, here is an example. If I move the mouse right, I want the gun to sort of jerk right. Like in COD MW2 or Halo or basically any FPS. I don't want the gun to remain static when I move the mouse. If I can make this more clear just tell me.
A way to make it constantly stay with the player and have the same rotation as it is to make sure the gun is a child of the player. If you mean when you aim with your mouse to follow the direction it's facing then you might want to check out a sample project in the asset store. The project deals with a characters head following the cursor. You cAn access the store by opening it up in your editor. Window->asset store. The project is free to download. You will have to create an account though.