Steve Tasitritsis 'ATLAS ARMS', 2704 N Central, Chicago and (later) 7952 Waukegan Rd. Niles, Illinois offered replacement barrels for Smith and Parker guns in the 50s and 60s using tubes made by E.S.C. Vickers (England) and fit and finished by Armaf in Belgium
http://www.littlegun.be/arme%20belge...armaf%20fr.htm
These barrels have a 1954 proof date code courtesy of Jim Akins.
There are Italian and unmarked presumably U.S. replacement barrels out there also.