They will cleany take a fox no problem. I have killed 20-30 coyotes with mine over the years, most of them were in footholds or snares, so it was a close shot, but I have killed them out to 50-60 yards with head shots when not in traps.

I have a carbon fiber barrel on mine, Hogue Over Mold stock, trigger job, millet rings, Nikon 4.5-14x40, and some other lil mods and it is a killing son of a gun!