I just noticed something from the pics Timer provided.
If you look he was comparing to the LPH which is from what I hear an AWESOME gun. But if you look the air cap on the REAL IWATA W400 it is much closer to the copy except for the fact that the air holes in the gold ring are the same size on the copy and different sizes on the real thing. So this might be that its an exact copy of this gun. Which would make it in theory a great primer gun wouldnt it? I couldnt find pics to post but here is a link to an ebay auction that shows a nice pic of the W400 Air cap.