The following tutorial will show you around the part 555 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
Regulations governing the procedure and practice for disapproval of applications for explosives licenses and permits and for the denial of renewal or revocation of such licenses and permits under the Act are contained in part 771 of this chapter.