District of Columbia Law, DC Code Ann.
Title 6, Chapter 23: Firearms Control, Subchapter 1 - General Provisions, Paragraph 6-2302 (2) has the following definition:
"Ammunition" means cartridge cases, shells, projectiles (including shot), primers, bullets (including restricted pistol bullets), propellant powder, or other devices or materials designed, redesigned, or intended for use in a firearm or destructive device"
So they clearly include pieces/parts under the ammunition definition.
Note to self: Do not travel to DC without vacuuming out the car and emptying out the purse ... Just in case ...