The 257's should work very well on big game. The 257 stw is simmilar to the 257 weatherby mag. And Roy weatherby used it to take larger african game animals up to cape buffalo. You can load the 257 cal. up to 120 gr. for big game or the 100 gr. is just right for deer with the barnes tsx or as small as 87 gr. I use the 100gr. barnes for everything. http://www.realguns.com/loads/257wm.htmAnd here is more info on the .257 http://www.shootingtimes.com/ammunition/ST257weatherbymagnum_031706/

So which ever 257 you choose 257 robert 25-06 257 weatherby mag or the 257 stw. You should be very happy with it.