You have it right, SWWASAS, a quickly fatal hit would have to be from a weapon suitable for North America's biggest game animals, moose, bison, elk, and big bears. That means a medium size bullet, 200 grains or better, from a high velocity magnum cartridge, or a large bullet, 400 grains and up, from a medium velocity caliber. Even then, as with any large target, placement is critical, and this is, I believe, at the root of the tales of Sasquatch running off after a shot, as if unhurt. The shooter pulled the trigger, maybe several times, but in the heat of the moment, did not aim carefully, and either missed entirely, or did only superficial damage if the shot did connect. It's known as "buck fever", nerves overcoming a steady hand, which is easily understood when faced with something large and possibly menacing. Shot control, aiming discipllne, is critical.