 In the United States, pen guns that can fire bullet or shot cartridges and do not require a reconfiguration to fire (e.g., folding to the shape of a pistol) are federally regulated as an Any Other Weapon (Title II).They require registration under the National Firearms Act and a tax in the amount of $200 to manufacture or $5 to transfer is levied.Pipe guns were first seen in the Philippines during World War II.