Right, Im trying to think about it not just from a war perspective though. I think its 7.62x39 most likely, but I wouldnt count out 9mm.
Not knocking the 9mm, but in terms of the entire world, the sheer volume of people constantly killing each other in the 3rd world isn't widely reported. In those countries, anything other than an AK takes a village genius to operate. No joke, in some countries there are people who don't have the ability to pull a trigger without opening and closing the entire hand. They can get by with an AK/RPD/etc, but a pistol is worthless to them. This comes from a friend that has to attempt training them for security in Iraq.