https://www.atf.gov/firearms/firearms-guides-importation-verification-firearms-national-firearms-act-definitions-1 https://www.atf.gov/firearms/firearms-guides-

https://www.atf.gov/firearms/firearms-guides-importation-verification-firearms-national-firearms-act-definitions-1 https://www.atf.gov/firearms/firearms-guides-importation-ver... > Any type of weapon by whatever name known which will, or which may readily be converted to expel a projectile, by the action of an explosive or other propellant, the barrel or barrels of which have a bore greater than one-half inch in diameter. Hmm, guess that would technically cover potato canons? Though the exemptions include > a device which is neither designed nor redesigned for use as a weapon :shrug: