I beleive the 17hmr will easily kill a fox,these animals usually weigh less than a big coon.There is a web page that compares the ballistics of the 17hmrto the 22mag and its big brother the 5mm rimfire magnum,which beats them both in down range energy,the web page is written by outdoor author Chuck Hawks check it out,I killed a 22lb bore coon the other night at 105yards with my 35year old rem. model 591m in 5mm rem. mag. wish you could still get rimfire ammo for it.CALL'EM IN CLOSE AND KILL'EM ALL!!!