Interesting thread. I use 308 for deer and echo what others have said, it’s unpredictable how the animal will react shooting the body regardless of caliber. This is why a long time ago I switched from body shooting deer to shooting them in the neck. I’m well into double digits of deer shot in the neck and I have a 100% drop on the spot rate going with the 308. We hunt with muzzleloaders as well and even body shots with those massive bullets at short distances are never guaranteed although the blood trail is so big a blind man could track with it. Given my experience and the size of deer I shoot I am in the camp that 556 is too small of a caliber. Even 243 is too small for my tastes because a perfect shot is required to dispatch the animal. And for reference my last deer I shot was in the 210-230 lb range.