17 Hornet on fox.. If you hit them in them square in the body or in the chest no problem. If you hit them (anything) low on the chest it's going to rip. I know of a person who use to visit here that was using the 17 WSMRF for coyotes... He shot one dead center in the chest with a 20 grainer and it ran about 5 yards.. He shot one in the shoulder and it ran 500 yards before it dropped... The coyote ran across a dirt field that the only reason they found the coyote... Yes.. I would shoot for the head and the good thing about the 17 Hornet ... They are so accurate that you can do this out past 100 yards..