Looking at the following ballistic table, the 77-grain .223 Remington goes subsonic between 800 and 850 yards for the atmospheric conditions used for this example. The energy at 800 yards is 236 food-pounds and the bullet has dropped 229.0 inches from the bore. One MOA at 800 yards is 8 inches. If the rifle is zeroed at 100 yards, you will need 29 MOA in elevation to be on target at 800 (229 รท 8 = 28.625).
.308 Winchester 168-grain Sierra Match King Bullet Ballistics
.308 Winchester 167 grain Lapua Scenar bullet ballistics
