I have a Remington 7005r being cut to either a 20" or 22" barrel that I will be putting a leupold mark 4 ER/T 6.5-20x50mm M5 on. It has 70 MOA of adjustment and in a perfect world which is usually not true I would have 35 up and 35 down. So lets say even with a few MOAs of wiggle room I zero and have 30 MOA up left plus my 20 MOA base giving my 50 MOA. Not sure the ballistics off the top of my head as this will be my first long range rig. I am guessing it will take somewhere between 40-50 MOA out of a 20" barrel? What do you all think? Just seeing if going to 20" is still plenty for my setup out to 1000 yards. Thanks guys.