I have shot three cats the first was with my bow the second was with my Smith and Wesson 45 and the third was with my 45-70goverment. before I blew my knee out I had taken clients and one used a 30-30 and the other used my 45 SW.. any caliber will kill them I have a buddy that shot them with his pistol I think it is a 38 or 45 so any heavier leaded load works but so dose the traditional stuff as well..I guess it is all hunter's preference..