.243
I read a good line somewhere that the only people that can't kill deer w/ a .243 are gunwriters.
The .243 was much maligned by my Dad and most of the hunters in our small community when it was becoming popular in the 60's and 70's. I was flabbergasted when my Dad bought one about 1995.
He began to hit and kill deer more consistently than ever before.
Dad's gone now and bamaboy and I have used his .243 to kill just a few. All with factory ammo that Dad had on hand, WW and Rem 100 gr SP.
Mine were close, velocity very high, and both shot through the near shoulder, quartering on. The heart lungs were a wreck. One passed through the other stopped on the hide on the off side. DRT and PDQ. Bamboy shot his double lung, top of heart, breaking the near shoulder, a complete pass through at 260 yds! That deer went about 50. This was on south land 125 lb deer.
If I had to consistently hunt 200+ lb deer w/ a .243 I'd invest in some premium ammo, say Nosler Partions, or one of the new bonded slugs so popular, and accept a bit less accuracy if I had too, in a trade for a stout bullet. But 100 std soft points will do fine if you avoid severe raking shots. You might not possibly always get an exit on big deer, but hit the vital cavity and he's done.