The 58 grain Hornadys usually shoot good in the 243 but I like a heavier bullets, 70-85 grainers. If I am going to shoot the light ones I might as well take my 22-250. But, that is the nice thing about the .243 you can shoot heavier or light bullets.
Find the factory amo the gun shoots the best and go have fun. Any factory amo in .243 is going to do the trick.