I am going to do a 4-16 on my future .308 build. But I have been told by many experienced shooters that a 10x is sufficient.
I do not have any exp with long range target shooting but hunting p dogs with the 7 rem mag having an adjustable scope is nice. kick it out to 4 find your dog and than zoom in to get a decent sight picture. a single power scope makes it a bit more difficult.
You sir, are a specialist in the art of discovering a welcoming outcome of a particular situation....not a mechanic.