Well, a shot with a .600 Overkill bullet penetrates 6 feet into solid oak. The game hunters would shoot more or less center-mass on the elephant and it would go out the other side. Just about any non-supernatural creature will drop after that.
Not really. Rhinos and Grizzly Bears can casually keep coming after that sort of thing (and do). Shooting a Grizzly Bear with a 30-06 is about as likely to stop it as throwing rocks at it. It might die later, but that doesn't help you in the mean time.
Debatably the Stress on such creatures shouldn't heal between scenes...but that's kind of an academic distinction most of the time with mundane critters.
The reason I am contesting Supernatural and Mythic toughness for animals is that this kind of ability is for creatures that can lose up major parts of their own mass or otherwise suffer tremendous harm and keep going.
Well, then a lot of mundane animals should totally have it. The Grizzly bear Lewis and Clark ran into got shot repeatedly, including through the eye, and still chased them off a cliff. Large animals are tougher than you're giving them credit for.
You'll also note that I don't give it out all willy-nilly. I think the only critters with higher than Inhuman on Toughness are the Elephant and the Orca. Both of whom would seem to warrant it.
The way I'd do the big animals would be Inhuman Toughness at most and a stunt to reduce stress from low-weapon-rating attacks (the reverse of lethal weapon that . That way they'd be resistant to harm from what animals normally resist but any big weapon would drop them. As is, an elephant could eat a blast from a weapon 7 rocket launcher and survive. It could even take 2-3 hits to take him out if the attacker's skill was only great or so.
Uh? Not really in any actual fight. At Great skill and a single FP that's a one hit kill for the most part. Especially if you consider being ground zero of large explosions like that to satisfy the elephant's Catch (which I probably would).
In contrast, a supernatural toughness black court vampire should take a weapon 4 armor piercing 2 shot to the torso that would open a fist-sized hole into it and keep going. Animals aren't supposed to do that.
Big enough ones absolutely do. Or take it and survive any way. The big difference between supernatural critters and most mundane animals is that the supernaturals are smart and/or agressive enough to charge the gunman. Most animals will panic and/or run, allowing the gunman several shots. This is actually a general (and important) note on animals: The few that keep coming after being wounded are feared far and wide by hunters, and likely enough to kill you: Wild boars, Grizzly Bears, Cape Buffalo, stuff like that.
Being charged by an Elephant is the sort of thing you should need to burn FP on surviving (say, the 2 or 3 it'd take to kill the critter). Well, unless you do this all the time (and know the aforementioned Catch).
I actually found a youtube video of some elephant hunters. They take some time to set up...and still require four shots to kill the creature. I'll admit they weren't using an Elephant gun, though. Here's the link:
http://www.youtube.com/watch?v=SP_AaKuIkqY