Please note that this Gun has a Magazine-Cut Off feature. When the Magazine is empty, the Gun will stop firing. Insert a new (loaded) Magazine into the Gun, and pull the Charging Handle to get it firing again.
The externals of the replica are metal where they would be on the real world gun. This includes things like the outer barrel, handguard, and receiver. If a real world gun has polymer parts then the gun will still be marked as full metal externals, examples of this would be an M4, where the Stock and Pistol grip are always made from Polymer.