Per the instructions on ATF Form 3310.11, Licensees who report the theft or loss of a firearm and later discover its whereabouts shall advise the ATF Stolen Firearms Programs and shall re-enter the firearm in the Record of Acquisition and Disposition as a new acquisition entry as from whom it was received.
The original disposition with the theft loss report MUST stay intact as the gun was out of your control for a period of time.
In FastBound, you will create a new Acquisition and enter or select the contact that returned the Item. e.g. Police department, shipping company, or your FFL. The acquire date will be the date the Item was returned to you or found in your inventory.
It is recommended that you make a note on the Item saying that it was previously reported as theft/loss and recovered.
You must contact the Stolen Firearms Program (and the local police to whom your reported theft if needed). to report the recovered firearm at 888-930-9275 or via email at stolenfirearms@atf.gov.