Re: Nightforce NXS 12-42x56. 100 Yard Zero Question?
What you are doing, of course, with a 20moa base is turning your (useless) DOWN elevation into UP elevation. Theoretically, if a scope is advertised with 40moa of elevation, it will have 20moa of UP and 20 moa of DOWN. Now, in reality, it is usally not that exact, and it has MORE up than down, say 22 of UP and maybe only 17 of down. The reality is, you don't know for sure until you buy the scope and try it.
So if you have 17 of down and put a 20moa base on it, you will be 3 moa short of being able to zero at 100 yards. But you will have 22+20 moa of up for a total of 42 up.
Of course you can do it this way, just shoot at 100 yards, 3 inches down is your new zero. So long as you are on paper you are good to go. After all you are setting it up for 1000 yards right? Shooting at 100 yards is just for load development and so forth right? If you are going to shoot at 100 yards competitively also with this scope you have a bigger problem (you will need two different bases).
If you are buying or spec ing a scope, it should have 50moa of total elevation so you have 1/2 that plus your 20moa of base for 45 moa of UP. That gives you some room to play with if things arent' perfect.
It really torques me when mfgs don't publish their elevation on their scopes. They need to do that all the time.