I own a Leupold Mark 4 3.5-10x40mm M3 and it does not have a built in taper. With my 308 zeroed at 100, I could only get to 800 before runing out of elevation.
I was told that all Mark 4's have a built in taper and bought Badger a 0 Moa base. I have since sold my 0 Moa base and bought a 20...