Use a good bullet, and the 243 works great.
The real question nowadays is: what does the 243 do better than a tight-twisted 223?
From what I can see so far, there is no discernible difference in wound channels between 223 and 243, with great bullets in each.
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This......
The edge the .243 would have for me is that If I had to shoot a deer at 400 yards Id rather have the .243 in my hands. At 300 it doesn't matter, cause Ive used both at that range, but after that I would prefer a bit more horsepower. JMHO
And lets see...........Ive shot exactly.......one.....deer at 400 in my life, so the little guns do most of the work these days....