If your gun shoots pretty well at 80 yards, you can probably zero it in for 150 also. But it will be shooting pretty high at 80 and 100 if you do. Use the bullet with the highest ballistic coefficient you can get accuracy from, and as big a powder charge that is safe in your gun AND that gives good accuracy at 100 yards. Then put a target out at 150 and zero it. After you have it dead on at 150, test it at 50, 75, and 100 yards just to see how high above the point of aim the bullet is striking at those distances.

It is NOT that a ML cannot shoot at the longer ranges (with good bullets). It's just that a ML has a pretty steep trajectory out yonder, and you have to shoot it alot at those distances in order to get used to how it performs.