The neck shot would be one of my last choices. After taking, and seeing elk taken with rifle, bow, and muzzleloader, the neck shot has not proven to be nearly as effective as say on a deer or antelope. Remember that the neck on an elk is large, with the areas to fatally wound the animal running at the top (spine) and bottom (jugular vein). I have seen elk shot in the neck with various calibers, round balls, and arrows. Few go down immediately (generally high neck shots at the base below the ear), with quite a few never to be found after the blood trail dries up. That being said, like many have discussed on so many other posts regarding "is it big enough?", how efficient are you with your .243? Knowing your gun, its limitations, where it is going to hit, etc. i.e. your comfort level, is parmount in any hunting situation. Also, dont forget to shoot a well made game hunting bullet! A well placed broadside shots at close range, and the ever risky head shot will definitely put one down. Good luck and shoot straight!