With a KJ, I've seen that all you need to do is cock the hammer and it will fire, regardless of whether a round has been chambered by racking the slide (this can cause it to fire, regardless of whether a round is chambered - which is unrealistic because with the real one, it would need a round to be chambered in order to fire and return the slide). With a WE, the slide must be racked first, otherwise the hammer will fall, but the gun will not fire.
Maybe this isn't clear...
YouTube- airsoft vs real steel 1911-A1 KJW, WE, cyber gun(delta colt & M1911A1)...spring & gas
This comparison demonstrates it.