I'm not all that big a fan of the 243, mostly because of the muzzle blast and heavy throat erosion. That said, the three biggest bucks I've ever seen were killed with 243s. Mine was the smallest at 175 gross B&C, taken at 150 yards. The biggest was my cousins, taken at over 300 yards and a mile south of me. My Brother in Law could of used a spear on his, was sitting with his back to a grown up fence row when he heard shots half a mile behind him. Got a look back there to see the monster running his way. Took the shot essentially straight up as the buck jumped the fence.
I haven't use my 243 much the last few years, mostly the 250 Savage and 257 Roberts.
i ain't either. the big bucks i have seen have been killed with the '06 or the 270. i have killed deer with the 25-06 but i think that its overbore. my project rifle is a 93 spanish mauser in 257 roberts, when i have the time to do it. when asked, what would be the caliber to give to my young son/daughter? i would say either the 7-08(factory loads) or the 7x57 mauser(handloads). well, i give that answer if you are young, old or middle aged. i've had the 6.5 creedmoor and i like it, i would say the 6.5 cm too.
back when i was young(14with wim m94 in 30-30. or so years old and up), me and my friend would go groundhog hunting. he was with his rem m788 with a 6x scope in 243 and i with a win m94(1972) with open sights in 30-30. i learned how shoot with it out to 200 yards. he, on the other hand, made some amazing shots. he took it out deer hunting and every shoot he took was a head shot. he finally gave up head shooting when he missed the deer's brain and was shot in the jaw. for 3 days he hunted the jaw stricking deer, when his uncle finally killed it. they took it home and skun the body to find that its spine was infected(pus). he called the game commision up and they took his deer and gave him another tag. he didn't shoot a deer till next year. he uses a win m70 in 270 and he lung shoots deer. i have tracked 6 or 7 deer(unfortunately, i never caught up with the deer) that weren't mine, that were shot with the 243. in every case, they were shot by a young boy(never a girl.....hmmm, i wonder why doesn't buck fever affect girls?). well anyway, the 7mm caliber (could be a 6.5mm) with 140gr bullets are good for deer. the .244" and the .257" are left to a guy/girl that knows a deer's anatomy and can shoot. this is just my $.02, your $.02 could be different than mine and thats ok.