Another trick that a local military dealer who also graces the Max and SOS, is to take original paper that was made out to a pistol but no a serial number. Many years ago I sold a nice ac44 P38 to him, a year later I stumble across the pistol on Auction Arms, the pistol then was sporting capture papers with my former p38's serial number. Called him on it and he admitted to the forgery and removed him from my contacts.. So in essence original paper, 90% original period theater content with a bogus serial.
I have many capture papers that list the the item, i.e. pistol rifle etc., however they have no serial numbers. This is very common in the PTO theater, "1 Jap Rifle", however capture papers in the PTO are much scarcer IMO.
Jeff