Yeah, if you beaned a tiger in the head at 25 yards with an Imp you would undoubtedly kill it. The true test of guts would be in letting a man eating tiger get that close to you in the first place. At that point I'll guarantee you nothing you're holding in your hands will seem big enough, but I guess a .22HP would be better than a sharp stick!
I guess Savage's ad campaign of a 100+ years ago worked. All these years later we're still discussing the merits of using Savage rifles on critters that view humans as a source of protein, and .22 HP's are still being bought and sold.