The following tutorial will show you around the part 771 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
The Administrative Procedure Act, 5 U.S.C. 559, provides that, except as otherwise required by law, privileges relating to procedure or evidence apply equally to agencies and persons. Therefore, an agency may rely on judicially-approved privileges to resist production of its files where appropriate.