I think 10 pounds is kind of standard for an ar-10 with optics, I've read a few threads on this subject and it's rare to see one dressed up for less. The M&P-10 weighs in at 8lbs in stock config. With out some skeletonization I feel it would be hard to get under that. The real value of the proof barrel on my modern Hunter was balance. That being said, I went from a heavy profile stainless barrel and the difference was night and day. Dressed up my modern Hunter is 11.8lbs but shouldered it doesn't feel half as heavy as before. Center of balance is the middle of the Magwell. I could shave it down a bit but don't feel it's necessary anymore. Also it's pretty hard to be lighter than a 223 action polymer framed rifle like the ACR, Not sure how it's relevant, is there a .308 calibre conversion? The RFB weighs in at 8lbs plus for a more relevant weight comparison.