The GMG
Grenade Machine Gun
Cal. 40mm x 53

Though perhaps not widely known, Heckler & Koch manufactures a 40mm grenade machine gun.  It is simply called the GMG.  (Granat Maschinengewehr)  This high impulse 40mm grenade launcher is a direct competitor to the Mark 19, currently in service with the U.S. military.  It is distinguishable in that HK made a belt that would allow the firer to load belts of grenades from either the right or left side of the gun, making the system totally ambidextrous.  

The gun is prominently featured in HK's newest promotional video called "The HK Weapon System."   It was torture tested in 1997 in the Yuma, Arizona desert as part of trials necessary to compete for future U.S. military contracts.  With optical and night vision sight mounts available, the GMG can operate anywhere, anytime.