My dad showed me a recorded show on his DVR. It was of John Burns...the guy that originally started the Best of the West series of long range shooting.
Anyway John has kinda been out of the spotlight for a few years and he was on this show with his new rifle line for long range shooting. He only makes the guns in 3 or 4 calibers and one of them is .243. Yep .243.
They were shooting and dropping antelope and mule deer out west at 500-600 yards with those .243s. Not only that but in his precision long range shooting video, they take a stock Remington 700 VLS in .243 and turn it into a shooting machine with just a few basic mods. On the target range it was easily shooting MOA out to 800 yards if I remember right.