a 243 is plenty enough gun for deer, some of the biggest bucks i have ever seen were taken by 243 and it drops them in there tracks,, if the shot is placed right then a arrow with a fieldtip will do the job , but some people like to overdo it and use 300 win mags and 7mm rem mags, were if you hit the deer in the tail he is going to fall , what an overkill