a machinegunfiringprojectiles twenty millimeters in diameter. Note: In the next sentence, LRH jokingly refers to the fact that you can't get the muzzle depressed enough. This is in reference to the fact that a 20-millimeter machinegun is a large weapon and is usually mounted in aircraft or an antiaircraft carriage. To depress the muzzle of a weapon is to press or push it down, to lower it. —AcademyLevel I Glossary - Approved November 1990