The rifle is tested, first day when hunter arrives in camp.
Once the test is done, the rifle is accepted as good one. If there is problem with camp rifle, this is the moment for hunter to speak up, and possibly take another one.
The responsibility works two ways:
- Lets say, hunter wounds the animal, puts blame on rifle? (hmmm, after initial test, very hard to pull that off, and very ungentlemanly... ) And then there are clients and clients - those who can shoot, and those who cannot shoot with any rifle...
In my opinion, wounding is moral, legal, and financial responsibility of the hunter. He should be able to handle a rifle, or not hunt at all. If he wounds, he has to pay.
- In different responsibility angle: hunter drops the rifle (by accident), breaks the stock, or good optics? Who pays the damage?
In my opinion, this is operational risk, taken by owner of rifle (outfitter).
Of course, speaking in good faith that hunter using the rifle is reasonable good rifleman, hunter, and handles the rifle with reasonable good care.
In conclusion, responsible solution to both problems, actually is question of ethics and courtesy, really.
In two hunts of my experience, i have seen in camps several calibers: 30-06, 375 HH, 300 HH, 300 wm, 223 rem... bolt actions. My guess, final choice of caliber by outfitter is made by availability of ammo in local shops.