My brother and I started hunting with "our 243" in 1969. At the time, we lived on Grandad's ranch outside of Powell, Wyoming. Since the rifle was a Remington, we reasoned that it would shoot Remington ammo best of all. We never lost a single animal and our list of kills grew every year. Mostly mulies and 'lopes but coyotes and a medium sized black bear were taken as the years passed. Core-lockt bullets are deadly!
We tried many ammo brands in the early 1970's. We found that Winchester Power Point produced the biggest holes.
Lately, I've enjoyed much target shooting with low cost PMP ammo from South Africa that sold for $9.00 per box a few years ago.
In my opinion, the BEST bullets for long distance accuracy include Sierra ProHunter, Hornady SST and Nosler Ballistic Tip.
Good hunting to you.
TR