Destructive device
In the United States, a destructive device is a type of firearm or explosive device regulated by the National Firearms Act of 1934, revised by the Omnibus Crime Control and Safe Streets Act of 1968 and Gun Control Act of 1968. Examples of destructive devices include grenades, grenade launchers, artillery weapons, and firearms (2) any type of weapon by whatever name known which will, or which may be readily converted to, expel a projectile by the action of an explosive or other propellant, the barrel or barrels of which have a bore over one half of an inch (.50 inches or 12.7 mm), excluding some rifles and most shotguns, both semi automatic and manually operated.