Mine would shoot 1.5" to 1.6" five-round groups at 100 yards with Federal Premium factory using 142 gr Sierra Matchkings right out of the box (with a scope and rings upgrade and torqued bases and rings). That is my baseline for testing. Never better, never worse. But I bought it with the intention of putting a Boyd's stock on it and pillars with Accraglas bedding and I did soon after.

One thing I will say is that the sporter weight barrel mine wears has to be rested to cool down between shots. After the first three I wait two minutes between shots. Even free-floated full length. But I see you tried working around that. I tried adding "pressure points" at different spots along the barrel in the foreshock but that just made things worse. I torque the front action screw at 65 in-lbs (aluminum pillars) and the rear at 40 in-lbs. The hunting load I was using this fall was a slightly compressed Reloader 19 and Sierra 130 gr Tipped GameKing (2.835" COL) that would put five in 1.10" to 1.25" at 100 yards. I also noted that a 1/16" jump (0.0625") was more accurate than the 0.015" jump I stared at. I'm still working towards that illusive MOA and will get back at it. I may add a chronograph to my stable now that the Christmas frenzy has passed.