The Colt-45 Magazine is the designated black cartridge of ammunition for the eponymous single-action, semi-automatic Handgun which we find inside the Cabinet Room with the Typewriter, or alternatively after entering the Mausoleum.
The Colt-45 was designed by John M. Browning, and was the standard-issue side arm for the United States armed forces from 1911 to 1985, and is still carried by some U.S. forces. It was widely used in World War I, World War II, the Korean War and the Vietnam War.
Adam: There's a label on this. Colt trademark.