Personal Firearms Record (P 3312.8) at a glance
What it is: The Personal Firearms Record (P 3312.8) is a list to keep separate from your firearms to assist police in the event your firearms are ever lost or stolen.
Where and when to file: This is a personal record only. The information will not be collected or maintained by ATF or any other Federal Government agency.
A filled-in Personal Firearms Record (P 3312.8) example: a rifle kept and a revolver sold

How to fill out Personal Firearms Record (P 3312.8), box by box
Firearms Description and Origin

Under Firearms Description and Origin, enter the Manufacturer/Importer, Model, Serial Number, Type and Caliber/Gauge.
A complete description of each firearm is vitally important to law enforcement in the investigation and recovery of your firearms and to your ability to prove ownership.
Enter the Date Acquired, the Cost and the Purchase Location (Name and Address).
In the Sold/Transferred to: box, enter the Name, Address & Date.
More rules for Personal Firearms Record (P 3312.8)
By completing this record and maintaining it in a safe location, separate from your firearms, you will be not only protecting your own property, you will be taking an important first step in the effort to prevent thefts and to keep firearms out of the hands of criminals.
If your situation is different
A firearm is lost or stolen
Immediately report any theft or loss of firearms to your local police.
Each year, thousands of firearms are reported lost or stolen. The owners' ability to adequately identify these firearms is central to law enforcement's ability to investigate these crimes and losses. Insurance claims and reacquisition of recovered firearms will also hinge on the ability to correctly identify these firearms.
Sources
[1] P 3312.8 (Revised August 2013), Personal Firearms Record, Bureau of Alcohol, Tobacco, Firearms and Explosives (the Official source link on this page).
