Abstract: A shotgun having identification grooves within at least part of the barrel, in a unique pattern which corresponds to the a recorded serial number of the shotgun (or of the barrel). The grooves are dimensioned to mark the polymer wadding which is normally included in a shotshell. The ejected wadding is thereby marked with identification data which can be used later to identify the gun.

Abstract: In a rifle or handgun, identification grooves, which are shallower than the rifling grooves, are formed in a pattern unique to a particular gun, providing a means of identifying the gun through which a bullet was shot. This identification can be used by forensic labs to tie a fired bullet to a gun having a particular serial number, even if the gun is not available for examination. The data mechanically encoded preferably include redundant bits which provide error control coding, thereby making identification both easier and more certain. The pattern is preferably formed by a mechanically-invariant process (such as EDM or photoengraving).

Abstract: A firearm in which a mechanical identification is integral with the surface of the chamber. Preferably the identification markings are elongated (ridges or grooves) in the direction of spent casing extraction. The extracted casings are thereby marked with a unique weapon identification number, which can easily be read by standard forensics methods.