bdc work with a given bullet weight and velocity. so if you go with a different bullet or velocity or mix of the two the further out you go the worse it gets.
for hunting accuracy either rifle will work. for parts availability and precision and ammo availability its the ar10 hands down
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." — L. Neil Smith