Montana Title 30. Trade and Commerce § 30-20-105. Exceptions

(1) a firearm that cannot be carried and used by one person;

(2) a firearm that has a bore diameter greater than 1 1/2 inches and that uses smokeless powder, not black powder, as a propellant;

(3) ammunition with a projectile that explodes using an explosion of chemical energy after the projectile leaves the firearm; or

(4) a firearm that discharges two or more projectiles with one activation of the trigger or other firing device.