Originally Posted by
Ridge Runner
sd has it right, the inner adjustment is what you turn to sight in, zero the outer ring, the outer ring is an older ballistic drop compensator.
the lower numbers on the outer ring is MOA, the upper numbers are hundreds of yards, now just find a cartridge/bullet combo that drops 10 moa at 500 yards when sighted in at 100.
RR
That means a lot of different ammo and range time !!!