''Firearm'', a stun gun or a pistol, revolver or other weapon of any description, loaded or unloaded, from which a shot or bullet can be discharged and of which the length of the barrel or barrels is less than 16 inches or 18 inches in the case of a shotgun as originally manufactured...
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''Sawed-off shotgun'', any weapon made from a shotgun, whether by alteration, modification or otherwise, if such weapon as modified has one or more barrels less than 18 inches in length or as modified has an overall length of less than 26 inches.
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''Shotgun'', a weapon having a smooth bore with a barrel length equal to or greater than 18 inches with an overall length equal to or greater than 26 inches, and capable of discharging a shot or bullet for each pull of the trigger.