PLEASE consider doing a .308 rail, preferably DPMS! The lightest rail I know of for a .308 AR is the Troy slick rail, and at 13.8" it's about 13oz including nut.
For people trying to get the lightest rail they can on a .308 AR, the Troy's the only real option we have at the moment. So if something comes along that's 5oz lighter than the current lightest rail, then pretty much there'll only be one acceptable choice if you're looking for a lightweight rail without giving up any features/functionality.

