This is what I found online: "From Answers.com: "In May, 1948, Smith & Wesson changed their simple "Made In USA" rollmark to a more complex four line bilingual version. This was to combat the many Spanish counterfiet revolvers being produced. For collectors, the 4 line rollmark indicates a definite post war gun." As I recall from other readings and discussions over the years, S&W was getting hosed by international competitors. In the primarily South & Central American marketplaces, locals preferred owning Smith & Wesson revolvers, but were not adverse to buying/owning much cheaper rip-off clones. It's no mistake that the early Taurus revolvers introduced to the US marketplace were almost exact counterparts to certain S&W models. They were already popular in regions that historically favored Smiths (but not the high tariff associated with a real one)." "FWIW I have been told that S&W used the mark to win a U.S. federal court case that effectively prohibited cheap Spanish copies of their revolvers from being legally imported and sold on the U.S. market. Protection of their trademarks on foreign markets was only a secondary goal, since many Latin American countries didn't respect U.S. trademarks at the time anyway. BTW the use of the "4-line" rollmark isn't universal anymore; newer Airweights wear a 2-line marking that reads: SPFLD, MA. S&W U.S.A."