Different governments, different departments, differing equipment. One constant in Africa is that there are few hard-and-fast absolutes, and generalities are commonplace, as are exceptions. But I'd think the .30-06 would be popular for a game department culling Ollies, particularly given the availability of .30-06 M2 armour-piercing.
I hear the AK47 is widely used by ivory poachers. Full magazines at a time I would suspect.
I'd expect, though depending on the availability and expense of AK ammo, not always, though I've seen one stitched by a belt-fed RPD light machinegun in the same caliber. In some parts of Africa, the guns are more common than a good supply of ammo, either of which can get the holder a death sentence on the spot.
Seperate AKs from several directions, particularly taking out the front legs at the knees first, is another way to go, though risking the chance for own goals from the other shooters. And like the RPG-7, the old FAL rifle with a Number 42 Zulu rifle granade is a pretty good stopper on Elephant. It's not alltogether a matter of ammunition selection, but that's an excellent beginning place.
-archy-/-