It would be impossible for an individual or separate company to have access to every serial number made in any year To keep or compile such data is a costly operation and those $$$$$ are the main reason that less expensive firearms produced prior to the GCA of 1968. It is possible to fit a shoulder stock on a pistol frame in place of a pistol grip, and, when combined with a 16' or longer barrel (see 'Thompson/Center Arms and the Supreme Court' below), a Contender may be legally converted from a pistol to a rifle or reversed.
