Description
The High Standard HDM is an American semi-automatic pistol equipped with an integral silencer. Based on the High Standard H-D pistol, it was adopted by the Office of Strategic Services (OSS) during World War II. Because of legal concerns during wartime, full-metal-jacketed .22 LR rounds were developed for this pistol.
During World War II, the HDM was adopted for use by the OSS. It later was used by CIA agents and US special forces units in the Korean and Vietnam War and supposedly up to the Gulf War. It's still used by the Central Intelligence Agency, the United States Marine Corps with 10 HDMS in use with Force Recon, and the United States Army Special Forces. During the Korean and Vietnam Wars it was also carried by Lockheed U-2 aircraft crews.
Source: Wikipedia