Chemical propellant spray
The Second Amendment links, however imprecisely, the right to bear arms with the existence of a well-regulated militia. Are permanent resident aliens included in the well-regulated militia of the country?
Massachusetts appears to prevent resident aliens from possessing certain firearms:
Persons who are not citizens of the United States, and are residents of Massachusetts may not possess large capacity rifles, shotguns, handguns or non-large capacity handguns. These persons may only possess non-large capacity rifles, shotguns, ammunition, and chemical propellant spray.