S&W serial numbered the Model 1917 (which included both the U.S. Army contract and the Brazilian contract, in its own series. 175,000 went to the U.S. Army (1-c. 175000); the total production is said to be 210,320. But things are complicated by the fact that S&W seems to have re-used frames and other parts from the U.S. contract to fill the Brazilian order. During WWI, the Army contended S&W wasn't making guns fast enough and took over the company. After the war, the Army took all the Model 1917's in work, plus those already shipped and those in the factory. When S&W got the Brazilian contract, it bought 25,000 guns back from the Army to fill the contract. Apparently, those were completed guns, which S&W reworked, but kept the original serial numbers. My Brazilian gun is 1640xx, well down in the U.S. serial number range. The frame has the U.S. eagle on it, and so do some other parts, including the barrel, but the U.S. Property marking has either been removed from the barrel or was never present.
Jim