As used in this act:

  (a) “Firearm” means any weapon which will, is designed to, or may readily be converted to expel a projectile by action of an explosive.

  (b) “Local unit of government” means a city, village, township, or county.

  (c) “Pistol” means that term as defined in section 222 of the Michigan penal code, 1931 PA 328, MCL 750.222.

  (d) “Pneumatic gun” means any implement, designed as a gun, that will expel a BB or pellet by spring, gas, or air. Pneumatic gun includes a paintball gun that expels by pneumatic pressure plastic balls filled with paint for the purpose of marking the point of impact.