I have seen the .40 S&W used on hogs in Florida and it was MISERABLE! One of the hunters that was with me on a hunt in Salem, Fl earlier this year shot a hog 8 times and didn' t even slow it down. Only 2 bullets ever reached the organs and the damage was virtually ZERO! I finally had to push him out of the way and kill it with a rifle.

With that said, out of the 2 calibers you mentioned, I would recommend the .257 Roberts and use the heaviest bullets that shoot accurately in your gun. Yes the .243 will work, it' s just that the .257 will work just a little better due to the availability of heavier bullets. For hogs I would also recommend a premium bullet like the Nosler Partition, Trophy Bonded Bear Claw or something similar. Hope this helps.