Undetectable firearms : hearing before the Subcommittee on the Constitution of the Committee on the Judiciary, United States Senate, One Hundredth Congress, first session on S. 465, a bill to amend chapter 44, Title 18, United States Code, to prohibit the manufacture, importation, sale, or possession of firearms, not detectable by metal detection and x-ray systems commonly used at airports in the United States, July 28, 1987.