OK, thanks again for the responses!

@Jamie: No, nothing is broken so far (as I haven't even shot this gun yet and don't have all the necessary hardware for that yet) and there is no real need as of yet to have 20 MOA base for this set up. I wanted to get it in case I move to longer distances with this gun at some point in future so I don't have to worry about changing it later but didn't want to compromise the performance of the scope at 300 too much. I may be splitting hair here though and thinking too much into it.. I did hear about some scopes having faulty reticle adjustments toward the end of their travel.

@foxx: I do realize that a scope can be optically centered at only one particular distance on a certain set up and am still curious which base would get me closer to that at around 300-400 yards since this is where I will be at most of the time in the near future.

@LoneWolf: Parallax adjustment starts at 25 yards I think on the scope that is going on this gun. May be 50 but it is well under 100 yards for sure, gotta double check what it is exactly. I never found myself in a situation that required shooting that close up to now though.

@sixone: Can't bore sight as I don't have the base yet. I have a couple of other sticks with 20 MOA bases and I was able to zero the scopes that are on 'em - not particularly expensive ones. I like and keep my zeros at 200 on .223 guns though. That way my POIs are relatively close at both 100 and 300 when dead holding which is convenient if a shot needs to be taken in a hurry. Did you mean a 0 base will get me closer to my goal @300?