Manufactured in late-1953 or very early 1954, the M13 was produced on government contract for the U.S. Air Force, who designated it the Model 13 Aircrewmen and requested the revolvers be stamped "M13". They were intended for use by strategic bomber crews for use as survival weapons. Weight conscious, they were originally produced with a lightweight alloy frame and cylinder with a steel barrel. The model was eventually rejected because of problems with the alloy cylinder with most destroyed by the government or S&W, making surviving examples rare and highly desirable among collectors. The top strap is marked "REVOLVER, LIGHTWEIGHT, M13". Back strap marked "PROPERTY OF U.S. AIR FORCE". The left side of the frame has a "P" proof mark. Serial number "C286749" is on the butt of the frame. The six-shot alloy cylinder, barrel, and extractor are numbered to the gun. The checkered grips have S&W medallions, with the right panel numbered to the gun. This revolver falls within the accepted Aircrewman serial range of C247000-C405363 ("The Standard Catalog of Smith & Wesson" by Supica and Nahas, pg. 147). The included factory letter confirms the current configuration as well as shipment to Norton Air Base in San Bernardino, California, on May 14, 1954. Other included documents (copies) pertaining to the revolver: The May 14, 1954 S&W invoice for 1,000 M13 revolvers ordered by the USAF and the U.S. government shipping invoice for the 1,000 M13 revolvers.