Moved to the Firearms accessories "For Sale" section. Please pay attention to the section in which you're posting. Also, it may help to give some details about the upper. Thanks, JW
I built many of these for Grey's during the last couple of years they were in business. If you can post a picture I can give you a complete spec list.
Most of them were built with 14.5 Lothar Walther stainless steel midl-lenght barrels with a pinned muzzle brake making a TOL of 16". I don't recall the manufacturer of the BCG but all the bolts where full-auto and cerakoted with micro-slick.
I own one of these and I can tell you for his asking price you are stealing it from him, if I had the spare cash I would snatch it up for sure. It is easily in the top ten best AR's on the market.
Your initial post mentioned chambering, price and the TB muzzle device. With your addition of 16", there's still not much. The pic from Jasonb helps but would seem to disagree about the muzzle device.