"Earth to the thread, earth to the thread,,, come in please!". How quickly we blame the barrel. Not that I'm defending any barrel maker, here. The OP did say that when he relieved some of the torque from the guard screws that accuracy seemed to improve. Not to the degree he'd like, but better. That says to me that there's a possible bedding issue. Most likely some stress somewhere. No one has suggested to check the length of the front scope mount screw to be sure it's not touching the barrel tenon, or to check the front guard screw to make sure it's not touching the bolt lug ever so slightly. I've seen that more than once, especially from someone who'll "mount the bases and scope myself" or from a 'smith that's not paying attention or has just got off the phone with someone with some far out notion that has taken up 20 minutes of his time, needlessly. As for barrels,,,, unlike investments, past preformance is a very good indicator of future results. Those who have been doing barrel work for a length of time know very well whos' barrels they prefer and trust, and those they do not. We can "guess" and blame components from now through Sunday, but that's all it is,, guessing. Without in hand examination it turns into a waste of bandwidth. If the builder can't seem to figure it out, have a different set of experienced eyes look it over.