Sounds like something amiss somewhere.
First off, is this while your trying to boresight it? If so your down is actually up. Aka your dialing the scope to the target, not moving the bullet hole to the scope.
What distance? 25 yards, 100 yards? Scope covers more distance per click the further out you go.
Barring all that, 20 MOA might get you on target, but if you need to adjust you might not be able to.
I'd check to make sure your existing base is good and flat. And sits flat on your picatinny. Bo burrs or such. Make sure your picatinny is flat also.
Good luck.
