I'm with #40 on this one. 300-400 is about max I'd call it "effective" on coyote sized critters. With that being said I did kill one a touch over 500 yards with my custom Remmy 700 223 about 8 years back. It was a total dumb luck shot on a running coyote straight away from me, got it on the 5th shot thru the back of the head.