Okay, so I'm thinking of getting a Leupold VX-II 6-18x40. It has 56 MOA of elevation, which means 28 up/28 down. I currently have a Nightfoce 20 MOA rail on my gun, so does this mean it will give me 10 up/10 down as well? Or 20 up? I ask this because if it is only 10 up this will put me at 38 MOA adjustment up for elevation, and I am looking for a little more. Best Regards, Hunter gun)

With your 20 MOA base, you'll have the same "zero line," but that line will be 20 MOA off what it would be with a 0 MOA base. Your zero will shift 20 MOA. So, that gives you 20 MOA more of travel in that direction (back towards mechanical zero), at the cost of travel in the other direction (away from mechanical zero). Top picture shows no cant. Zero line bisects the scope travel. Bottom picture shows "20 MOA" cant. Zero line is offset to the top of the triangle, so you have an extra 20 MOA of travel on the large side.

Just to complicate things a little... In the real world, you will likely not actually end up with a total of 48 MOA elevation available. That's because it's normal to use up some elevation when sighting the rifle in. This can vary from rifle to rifle, but sighting in can easily use up 10 MOA or more. If that's the case you may well end up with only 38 MOA UP available. While that is a usable number., you could go to a 25 or 30 MOA base and gain elevation back, but you might want to look at some other scopes before you make your final decision. I'm not sure that particular scope is the best choice even in Leupold's line up. TC

Just to mix it up... What if you were to get the 20MOA base... AND the Burris signature rings with the MOA offset inserts that could grant you up to 30 MORE MOA if you buy the kit for like 14 bucks... But thats just an idea.. your scope is going to be tilted something serious!

That is still a lot of adjustment, you did not mention caliber/load/etc. . . but even at 28 MOA that should get you a long way. I normally use a 10 MOA base and the Burris rings if I really want to stretch. Most of my normal hunting shots are 300-600 yard so 10 MOA suites me fine for centering the reticle when dialing. I have more when needed. But we all have a different definition of Loooong.

That is exactly right. Get a good Ballistics calculator and when you "estimate" your drop, convert the drop into MOA increments. Compare the two. See what your max range is with your limited internal adjustment. I think you will be surprised at how far that 28Moa will take you!