In 1951 and 1952, Colt supplied a small number of extremely lightweight revolvers to the US Air Force, designated the M13 Aircrewman. These guns were very similar to the commercial Colt Cobra; .38 special 6-shot guns with aluminum alloy frames and cylinders with a loaded weight of just 11 ounces. Only 1189 were made, and they were issued with a special low pressure loading of .38 Special ammunition. It was designated M41 and fired a 130 grain FMJ bullet at just 725 fps. This reduced pressure loading was safe in the aluminum cylinders of the guns, but nothing prevented a person from loading and firing standard .38 ammunition - which was definitely not safe. In 1959 the Air Force decided that the potential hazard from standard ammunition was not worth the slight weight reduction of the aluminum cylinder, and recalled the guns for destruction. Only a small number survived to get into the commercial market today, making the Colt Aircrewman a very scarce revolver indeed.