First of all, how high is your scope center line, as compared to your rifle bore. You definitely should not be low at 50 yards-you have a problem. Here is how it should be.
25 yards-1/4 to 1/2 inch low
50 yards-1/4 to 1/2 inch high
100 yards-1-2 inches high
200 yards-1-4 inches low
It is highly unlikely you are 2 inches low at 50, and high at 100. If you are, then you have a problem. Remember the higher thescope, the greater the difference in trajectory at short distances(because of line of sight). Also high scopes tend to have more mounting, or moving problems.
If you want to shoot 300 yards, then add 1 1/2to 2 inches at 100 yards. Tom.