Tom,
I double-shouldered (and spined) a Texas whitetail with a .243 in December. It was a doe, though, so maybe that doesn't count--and the bullet was a factory "blue box" Federal 100-grain, so maybe that doesn't count either.
The bullet also exited. Does that count?
No, unless it was a .243 'Magnum' of some sort.
Your 'sample of one' was obviously a fluke.
