I have a 20 MOA base on my 284 HB. It carries a sightron scope. That scope will not zero inside 200 yards. Even then it is bottomed out nearly. But that is a rifle intended for 1000 yards.
More than likely you would be better served by a 10 moa base.
It takes a pretty poor scope to not handle a 20 moa cant and still zero at 100 yards. More likely your mounting system is not true to the barrel and has more cant built in than you think. Either that, or your windage adjustment is way off to one side (again because of an out of true mount), which reduces available vertical adjustment in the scope.
For reference, 20 moa is roughly equal to 6 mils. That's not very much, and most scopes intended for dialing can handle it easily with plenty to spare.
