On a federal level, all firearms manufactured for sale in the U.S. are required to have serial numbers stamped on them, making the legality of “ghost guns” without serial numbers a grey area in the United States.
The lower receiver is the part of the AR 15 that contains the fire control group (the trigger, disconnector, hammer, and fire selector), so this is the only portion of the AR that must be marked with a serial number, manufacturer's name, and so on.
A gun serial number is a unique identifier assigned to each firearm by the manufacturer, and it serves as a crucial tool for tracking its history and ownership.
Many guns have no serial number at all (serial numbers were not required in the US until 1968, and are still not required everywhere).
This is important to track where people get the guns from and who is responsible for them. For this reason, it is also illegal to possess a gun with an altered, changed or removed serial number. If a person is caught possessing a firearm with an altered serial number the person may face gun charges.
PMFs are also made without a serial number placed by a licensed manufacturer at the time the firearm was produced. However, not all PMFs are illegal and not all firearms are required to have a serial number. ATF has compiled some information on the different types of PMFs and things to consider while owning one.
If the firearm has no serial number, and never had a serial number, the lack of a serial number renders the firearm illegal. Except a non-NFA home manufacture that you have no intent to sell, which we will explain later.
Federal statutes, such as 18 U.S.C. § 922(k), explicitly prohibit the removal, obliteration, or alteration of serial numbers on firearms. Convictions under these statutes can lead to: Imprisonment: Up to 10 years in federal prison.
Possession of an unregistered firearm is also covered by federal laws and can also be charged as a federal offense. 26 U.S.C. § 5861(d) provides that it is a crime for a person to receive or possess a firearm not registered to them in the National Firearms Registration and Transfer Record.
In California, the ghost gun trend started as a way to end-run California's sensible gun laws, particularly the laws on assault weapons.