What is the best variable magnification for a 308 when using it primarily for 400 to 600 yards and sometimes using it for 1000 yards? I am thinking about purchasing a Nightforce 3.5 - 15X50, but would buy a 5.5 - 22 X 50 if that would fit the bill better. HELP! By the way, what are the reasons for your answers? Ya...you thought this would be an easy reply...I think?...