A lightweight .308? 8 lbs or less, empty, w/o optics, with a free float tube or quad rail and at least a mid-weight 16" barrel?
I put together a PA-10 and got it down to that weight by reprofiling the barrel. That's with an 18" barrel plus flash hider, 15" MI free float rail, and Magpul furniture. It goes 9 lb scoped with an empty Pmag, right at 8 lb or a hair under without optics. The PA-10 receivers are lighter than the DPMS equivalents.
Faxon sells an 18" 308 barrel that is about the same weight as mine.
Don't know what your criteria is for reliable though. My PA-10 hasn't malfunctioned once, but some small parts needed extra fitting out of the box. Don't know if they've changed that yet. Once parts were fitted and got the gas adjusted it has been 100%.
