This handbook reports the results on the techniques of the criminal investigator in the performance of serial number restoration. The handbook is primarily focused for use on handguns but can apply to any object which have markings which have been obliterated intentionally or unintentionally. All known methods are compared, gun metals are categorized, and optimum methods for individual metals are described. The handbook is written in such a way that it can be used as an indepth textbook for the novice and yet be very useful to the experienced criminologist as a reference manual.