(1) M-16s require much more maintenance than a Kalashnikov or its Soviet-era ilk. Your average African militiaman is simply too poorly educated, untrained and unfamiliar with mechanical devices to really maintain anything complicated.
(2) The primary weapons dealers in Africa are either Chinese, Ukranian or Serbian. Their wares are almost exclusively former Soviet weapons, or their modern counterparts.
(3) Africa is awash in Kalashnikov ammo. It makes military and business sense to keep your men supplied with stuff that can easily be repleneshed locally.
There are also quite a few Czechs from the old communist days *Omnipol* trade group days still around, and there's a lot of flogging of Romanian AKs, easily spotted by their distinctive forward pistol grip not unlike that of the old Thompson SMG but reshaped to accomodate the AK's folding buttstock.
Those things turned up quite a bit in news footage of the festivities in Iraq, as well as in the Palestinian areas of Israel and elsewhere, and likely will continue to do so.
