If we assume that technology has reached the point where napalm can be made from the same stuff as electricity, gunpowder and bullets then we're messing with some pretty fundamental atomic properties within an ammo container. Once you reach that point, you wouldn't make ammo that contains neurotoxins that take people down in 3 shots, but rather 1 that only has to graze the skin. You'd also find it pretty hard to maintain the 3rd world "everything has broken down" deus ex world.
Sorry. unified ammo *breaks* the immersion, it doesn't promote it except to people who have no concept of what it would require.