I wouldn't blame all negative 243 comments on poor shot selection.
My experience with the 243 was terrible and I'm glad to see others that have had better results. I finally ditched mine about a year b4 Nolser brought out their Ballistic Tip for it. I think that is as good a deer bullet as there is. I was using Sierra 100 gr bullets and was losing more deer than I found. The ones that I did find after running off hundreds of yards were shot in the shoulder/chest, but still took off leaving no blood trail. He might die within 10-15 seconds, but a deer can run along ways in 10 seconds.
I used that Mod 70 for over 10 pitiful years, always swearing to get rid of it b4 next deer season. But I lived out in the country back then and carried that rifle with me every day and shot it well too. I shot crows, skunks, armidillos, turtles, pine cones, you name it I could hit it, including deer. That's not brag, I just shot it alot and new I could hit what I was aiming at. That is what finally did it in for me. I ran out of excuses one day, finally realizing that it just had too small a hole at the end of the barrel.
I lost a very nice buck one morning that was standing still, broad side, about 50 yds and I had a good rest, no hurry, and a rifle that I shot often and had confidence in, at least accuracy wise. He staggered a bit and took off. Long story short, no blood, no trail, no deer. I went that afternoon and traded it. It was a good rifle, perhaps better with newer bullets, but it was strictly a farm yard varmint gun for me and I couldn't afford to buy another without trading. Probably the most accurate rifle I've had.
I would never argue that power is better than shot placement, but I think having both is even better.