I just purchased this scope for my Bushmaster AR .308. Can someone explain in detail how to utilize the turrets. I understand how to sight it in utilizing windage and elevation, but I don't understand the turret on top of the scope, or the "zeroing" feature, or how to use it. I was amazed that there weren't instructions that came with the scope, and even more amazed that nobody in customer service at Nikon knew anything about it. Anyway, I have the scope and it bs mounted. Now if I only knew how to properly use it. Any help would be greatly appreciated.