A firearm comprising a gun barrel for accommodating a desired round of ammunition
having a bullet, a shell casing and a primer. The gun barrel has a firing pin associated
with a chamber of the gun barrel and the firing pin is activated by a trigger assembly.
When the firing pin is activated by the trigger assembly, a striking surface of
the firing pin strikes the primer and discharges the round of ammunition to propel
the bullet out of the opposite end of the gun barrel. The firing pin, the interior
surface of the barrel, or some other surface which contacts the shell casing carries
a unique identifying indicia. Upon discharge of the round of ammunition, the component
of the firearm carrying the unique identifying indicia transfers an impression
of the unique identifying indicia to an exterior surface of the shell casing to
identify that the shell casing was discharged by that firearm.
