Point taken on "Lord of War". I have heard (not from a movie) that the U.S. left behind many M16s in Vietnam, so I figured it would make sense if the same happened in Lebanon. But that's what I get for trusting Hollywood.
Hezbollah actually runs gun factories? I do realize that many of the militants manufacture weapons, but I always figured the stuff they made was pretty simple. The rockets and RPGs I see are crude stuff, so I never would have imagined they could build something like an M4 (like that one Hezbollah gunman is holding) and build all the plastic parts and all that.
AKs would be simple to make, though - I have seen images of tribesmen in Pakistan (mostly NWFP and FATA) who can make exact copies of the AKM and Type 56. They're pretty good copies, too, although I think they lack chrome-lined barrels.