docrob, Don't let specifications get in your way …. practical solutions are always the best, no matter what brand you buy. Let's start at the beginning. Assuming you want to use your 308 for hunting, there is a practical max range of about 225 yards. Beyond that distance, there is still plenty of power to kill Bambi, however you will be hard pressed to hit the kill zone without a rest and a trajectory chart. Further, a typical 308 will shoot pretty flat out to 225 yards then the bullet starts dropping at a much faster rate. This will complicate issues because you won't know how much "holdover" is needed for a kill shot.
Magnification tends to be more of an enemy that a friend. For off hand shots, any magnification over 4X will be very difficult to hold still enough to keep the crosshairs from jumping around. Higher magnification limits your field of view, which makes locating Bambi more difficult. Larger objective lenses do transmit more light but they also add a lot to the weight and length, plus it makes it more difficult to mount with proper eye relief. In most states, it's illegal to hunt before sunrise or after sunset so you really don't need a scope with an objective lens more than 40mm. An adjustable objective lens (AO) or a side dial are necessary to keep parallax under control with magnifications over 9X. Problem is …. when you spot Bambi, you just don't have time to be knobdickin' ….. by the time you set magnification and adjust parallax, Bambi is no where to be found. Most hunters find a 3~9X 40mm scope without AO or BDC is the most practical. That's because the shooting industry says you should have 1X magnification for each 25 yards, which works out to 75~225 yards with a 3~9X scope.
If you don't plan to hunt with your 308, most of the above can be overcome with a decent bench rest and as much magnification as you want. Once you get 10 or more posts, you can download a free document from the Forum E-Library, titled "Scope Dope". It will answer most of your questions and give you a better understanding of optics. Here's a link: https://rugerforum.net/e-library/61505-scope-dope.html