The Mk 19 grenade launcher is an American 40 mm belt-fed automatic grenade launcher that was first developed during the Vietnam War.
A Mk 19 40 mm grenade launcher mounted on an M3 tripod
US Navy crewman fires a Mk 19 Mod 0 in July 1969
U.S. Navy sailors fire a Mk 19 40 mm grenade launcher during a training exercise in March 2003.
Mk 19 in use by Polish Land Forces
The word mark, followed by number, is a method of designating a version of a product. It is often abbreviated as Mk or M. This use of the word possibly originates from the use of physical marks made to measure height or progress. Furthermore, by metonymy the word mark is used to note a defined level of development or a model number.
Two Ford Mondeo sedans, a Mk II (grey, left) and a Mk III (blue, right)
VW Golf Mk III