OOP: Where to stop Abstracting

class Player {} ;/// contains Weapons
class Weapons{} ;/// contains BulletTypes
class BulletType{} ;///contains descriptions of Bullets
class Bullet{} ;///extends PlaceableObject and RenderableObject which can be placed/drawn respectively
class PlaceableObject{} ;///has x,y,z, coords
class RenderableObject{} ;///an object with a draw() command
class MovingObject{}; ///an object with a move() function