That is correct. See MGL Chapter 140 Section 121 for the definition of ammunition:
“Ammunition”, cartridges or cartridge cases, primers (igniter), bullets or propellant powder designed for use in any firearm, rifle or shotgun. The term “ammunition” shall also mean tear gas cartridges, chemical mace or any device or instrument which contains or emits a liquid, gas, powder or any other substance designed to incapacitate.
Thanks wahsben and M1911. I thought that was the case, but I wanted to make sure it was accurate info. And I wanted to make sure the OP didn't get jammed up with incomplete info.