That .223 will kill a Tyrannosaurus Rex at 1000 yards with hit to the big toe. Of course you'll have to wait for it to die from the infection after it steps in Stegosaurus poop.
Under field conditions and assuming you expect a first shot hit, you will need to be an expert wind doper to hit a coyote at over 300 yards. I've seen imperceptible wind gusts move the 55 grain bullets 8-12" at 300 meters. Through the winter, I keep a bait pile located 350 yards from a shooting station behind my house. Some days I can hit an 8" circle and some a 3" circle mainly due to wind gusts. An 8" group only hits a coyote about 1/2 the time.