Where is the gun serial number?

Answer 1

All depends on the gun itself. On a revolver, it'll be somewhere on the frame. On an automatic pistol, it's usually on the slide, although some (such as the Glock) have it on the lower receiver. On rifles and shotguns, it'll typically be somewhere on the receiver, although some older military rifles will have it in a number of places - Mosin Nagant rifles, for example, have serial numbers on the receiver, magazine, buttstock, and bolt - in the case of these being mismatched, the serial number on the receiver, or else the one placed on it with the importer's mark - is to be considered the correct serial number.