I know several people that use 243 Win for deer, including myself(years ago). I've built a few 25-06's for myself and others and have used them on deer too. Both are nice cartridges but but you can do a lot better. For instance: You can get more velocity from a 100 grain bullet with a 260 Rem than with a 243 Win. And more velocity with a 308 Win with 130 bullets than with a 25-06 with 115 grain bullets.