The following tutorial will show you around the part 478 landing page.
27 CFR Part 447
Importation of Arms, Ammunition and Implements of War
27 CFR Part 478
Commerce in Firearms and Ammunition
27 CFR Part 479
Machine Guns, Destructive Devices, and Certain Other Firearms
27 CFR Part 555
Commerce in Explosives
27 CFR Part 646
Contraband Cigarettes
27 CFR Part 771
Rules of Practice in Explosive License and Permit Proceedings
Effective date is the date this part was last amended
Where a firearm or ammunition business is either discontinued or succeeded by a new owner, the owner of the business discontinued or succeeded shall within 30 days thereof furnish to the Chief, Federal Firearms Licensing Center notification of the discontinuance or succession. (See also § 478.127.)