To find a serial number on a gun, look at the receiver or frame, according to the Bureau of Alcohol, Tobacco, Firearms and Explosives. This is a legal regulation, and on firearms from Jan. 30, 2002, or later, the serial number must have a minimum depth of 0.003 inch. The importer must also ensure that each serial number is unique.
In addition to the serial number, gun manufacturers must also imprint the firearm with the name of the brand, the country of origin, model if available and caliber, explains the Bureau of Alcohol, Tobacco, Firearms and Explosives. The name of the importer and location must also appear on the firearm. As with the serial number, each imprint must have a minimum depth of 0.003 inch.
The importer must ensure that this information appears on every firearm that comes into the country, and if the information does not appear, the importer must imprint the firearm within 15 days, states the Bureau of Alcohol, Tobacco, Firearms and Explosives. There are exceptions to firearm identification rules in some cases, such as if an importer asks for another form of identification. Another exception to the rule is when the device is a destructive device, but the importer must apply for an alternative form of identification. Silencers, machine guns and firearm mufflers are also exceptions in some cases.