OK....1st off,If your longest shot is going to be 100yds, then have it zero at 100yds. 1/2" high at 50 will put your 308 at around 1 1/2" high at 100. Is that OK for hunting??.... sure it is, but its not needed unless you're going to be shooting out to 200. Secondly, at your 50yd range, a bullet that your gun "likes" should one hole group{or at least clover leaf}. So, find the bullet your gun likes best, then go to that bullet manufactures website, look up your exact bullet in 308, and look at the ballistics chart for it. For example, a Fed Premium 150gr Ballistic tip 308 zeroed at 100 is .2" LOW at 50.
Sorry to disagree guys, but its a chemical reaction sending a projectile at high velocity....so it kinda is "rocket science".