For deer any thing will work just know what it will do and how good you can shoot in hunting conditions..243-25 06-270 or 30 cal. and up for elk size game.IMO. the previous 3 have about the same drop 308 and 30 06 a little more. 243 best for south deer size game- 25 06 $$ and harder to find a round your gun likes- 270 if not to much kick for you a flat shooting hard hitting and a little over kill energy out to 500 yrds... 243 energy out to 300 yrds more than anyone should be shooting and asking cal. gun ???? but you cant go wrong get what makes you smile.