The 243 will absolutely work well on deer. My wife used one for years. She has taken just about as many deer as I have. Just use the right bullet. No light weight, light jacketed varmint bullets. Two years ago at my BIL's hunting in the Nebraska National Forest, had a 3X3 appear, not moving right, put him down. Had been hit right on the shoulder knuckle, baseball size chunk missing bones and joint busted up. No idea what caliber, no penetration and a wounded deer soon to die deer. I am not a fan of the 223/5.56 for deer, but with a good bullet and some accuracy they will and do work. Just pick the right bullet. As to shoulder shots I do not like them, they can ruin meat. I will how ever take a shot that is offered if I need to.
