mokepole,
Have perhaps traveled a little more than most hunters (but not nearly as much as some), and have seen rifles separated from ammo quite a few times during air travel--due to many airlines insisting the ammo not be in the same case as the rifle.
Sometimes there's a rifle the hunter can use instead, but not always with the confidence they would have with their own rifle--or ammo. Partly because there sometimes isn't time, or adequate facilities, to get used to the borrowed rifle--including sometimes triggers that kinda suck.
Have seen the hunter's rifle and/or ammo show up after 2-3 days, but have also seen neither show up for the entire hunting trip.