The China Lake Launcher, which is the M79 but basically better in almost every way compared to the M79. Of course, somehow the Army didn't catch onto the fact that the China Lake was far superior and it was only issued to the respective branches's special forces.
If the M79 was the best grenade launcher available at the time, it's cousin was better in every way possible. The problems inherent to a break-action weapon with only one barrel? Pump action and tube magazine, carrying a maximum of three 40x46 millimeter grenades. The sheer weight? According to operator testimony, China Lake was lighter and the aforementioned tube magazine saved much of the burden in carrying extra grenades. Fire rate? Skilled operators can fire off four rounds before the first hits the ground.
It's like a grenade-spewing tube of death, man. Sure, it's about as rare as Das Rheingold, genuine Wootz Steel and Greek Fire combined. But it sure does leave one hell of a impression.