With respect to Joe, he is correct with his advise on the 243.
Let me qualify why I do not like that caliber, and it has nothing to do with me thinking it is an inadequate caliber for deer. It is not.
Many years ago I took a friend on a hunt and placed him on a mountain about 50 yards off the property line for the hunting club lease next to ours. He had many years of experience and many deer kills with his 243. Nothing unusual.
From that spot, he shot a big buck through the lungs with a hunting bullet/factory ammo. Same stuff he'd used for years. The buck took off running down the mountain parallel to the fence-line. Ultimately it jumped the fence and headed 90 degrees into the next door club where 2 other hunters put the buck down with their 30 cal rifles.
Regardless that my friend placed a killing shot, he did not put the buck down and the other hunters claimed it. There was no argument from me. This would have been the biggest buck my friend would have taken at the time. The fact is, the deer was running and dying at the same time, it just didn't die fast enough and made it much further than I like to see with a well placed lung shot.
This is just the way I roll but if I see only ONE instance where something is not to my satisfaction, I will never use or promote it. The same thing happened with my first experience in TX with a buddy on his first pronghorn hunt. He shot his buck at 234 yards with a 308 and factory Hornady SST ammo. The buck took 4-5 shots to die and the bullets were exploding on the shoulder blade with NO penetration to the vitals. Hence, I will never ever use an SST bullet.