Dale,
Just buy it and tell us how it works. But you do need a rangefinder to get your distance unless you are hunting the same place and have previously measured off reference spots. This is the same concept that BSA is using on their Sweet series of scopes. I have a Sweet 17 that I took p-dog shooting and it did good, we also had a range finder and a small wind meter. Also, the Sweet 17 is calibrated for the factory 17grain bullets, so when I switched to the 20 grain bullets it was off a bit. Cabelas is also offering scopes that have bullet drop compensators. Many years ago, I think early 1970s Bushnell came out with a scope that had a Bullet Drop Compensator. Just considerate it another tool and use it as it was meant to be. Developing a click table has the advantage of learning more about your loads and how they behave and also allows you to change your load or have multiple loads and not have to worry about which turret you have on the scope.