Manufactured from 1951 to 1957 for the U.S. Air Force on the thinner Model 12 aluminum K-frame. Chambered in .38 Special and have an alloy frame and cylinder. Pilots and other flight-crew members carried them for emergency use. The Air Force ultimately rejected the model because of problems encountered with the alloy cylinder, and most were destroyed. Because of this, the Aircrewman is one of the rarest modern-day Smith & Wesson revolvers. Serial numbers in C247000 to C406000 range. It is not known how many still exist, but estimated at 250. Genuine model is seldom seen for sale. Numerous fakes have been documented, so it is strongly suggested that a knowledgeable S&W expert be consulted for an appraisal.