Possession of Firearm Having Altered or Obliterated Serial Number is a crime in which a person owns, possesses, or controls a firearm with a serial number that has been modified, changed, removed, or obliterated. Types of Possession of Firearm Having Altered or Obliterated Serial Number include: 1. Altered Serial Number: This involves changing the serial number to a different number. 2. Obliterated Serial Number: This involves defacing or removing the serial number, so it is no longer legible. This crime is usually punishable by a jail sentence, heavy fines, and other penalties such as probation or community service.