Not sure what a 243Rem is, but the 243 Winchester has a rough past.
It is notorious for having random(sometimes violent) pressure excursions for no apparent reason. Call any of the bullet/powder folks who do their own shooting; and ask them about it....
Standard 243 twists are a bit slow for current heavy match bullets, and back to the case... So you don't see many on the firing line in matches. Something like the "Six"(6mm PPC) is a MUCH better case choice for match shooting, Pretty much owns alot of the shooting matches.

I love my 308, I like my 243 for coyotes(because Z-max's are cheap) but I don't use it for much else. With light bullets, the 243 & 22-250 are only a few small grains apart for loading: Lots of powder, lots of heat, small bore to erode upon.