at long ranges the 06 would be waay more acurate then a 243. the 06 is a heavier bullet and wont be as effected by wind drift as much as the lighter 243. if you friend is right then why were so many police dept. using 3006's/308's as sniper rifles instead of 243's. granted the 43 if flatter shooting but at long ranges it also isnt carrying the energy the 06 is either. there a lot more points and examples and bal. coef. i could give you but i dont feel like typing it all tonight lol