That's a new one on me. The M79 was a shoulder fired grenade launcher that is now incorporated below the rifle barrel of the M16 type rifle barrel, I believe the combination is now called the M4 and maybe "maximus" can clear that up. They did have belt fed hand cranked grenade launchers that could have been mounted in the manner described.
huh, what, oh sorry i was sleeping, GUNS,
Dear Lord Hillary, the offroaders are talking about assult weapons again What do we do???
ok anyways, the M79 is a shoulder fired, break barrel(like a shot gun) single shot grenade launcher
not a good weapon to mount, or carry for that matter, these lead the pack, imagine walking thru the jungle and having charlie pop-up in front off you, instict says pull the trigger, make him die, HE round (highly explosive) is not a good round to fire with close distances, think about it
the M-4, is much like the M-16, same 5.56ammo, same magazines, only shorter with a flat top and collapsable butt stock for CQB (close quaters battle) the M-4 was slated to replace the M-16, but now the Maarines are crying again for new guns, the M203 is what is now used to fire the 40mm grenades, it attackes to the bottom of the barrel on either a M-16 or a M-4
M-4
M-4 w/M-203
M-16
the belt fed monster you speak of is the Mk-19(mark-19)
in a perfect world if you pulled the trigger and left it pulled, this gun would put in the nieghbor hood of 375 rounds down the bad guys throat, all the way out to 2200meters, who wants one on the crew cab?
oh yeah it also fires the 40mm rounds as does the M-203, as did the M-79, these are all very impressive weapons belonging to and at the disposal of the US military, but no where near the coolest, i mean to tell you the list goes on forever, the F-15,-16,-18,-22,-118 stealth fighter, we have planes that work of video game controls, its amazing we all we have, this is my personal favorite, in F9K9's day these where called "Puff the Magic Dragon"
now those are big guns