Goodsteel has it right. 243's are barrel burners, especially if you shoot 115's at 3150. That's hot.
I understand the allure of shooting something with really low wind drift, but what does it matter if your gun won't hold a group after 800 rounds? You're better off shooting something with decent barrel life (ie 308 win, 260 rem, ect) and working on your wind reading ability.