Firearms evidence must be properly marked in order that it may be readily identified in the future. Firearms should be marked by an electric, diamond, or carborundum tip inscriber. When those parts of the firearms which leave imprints on the bullet or cartridge case are readily removed and interchanged without tools, each assembly group embodying such a part should be marked separately. Generally, the parts should be marked with letters or figures; the case number, the appropriate date, and the written initials of the crime scene technician so they can be identified later.