My 28 N has a Krieger #5 26" barrel with 8.4 twist. It shoots the 195 very well, as well as the 180 VLD-H and the 169 Hammer Hunter. So that twist rate is capable of handling the 195s in that barrel. I am a firm believer that each barrel is different in the way it handles heavy for caliber/long high BC bullets.
I have a 10 twist 270 that shoots the old round nose 150 gr Winchester ammo (I was using a couple old boxes to break in the barrel. Talk about surprised) into better than 1/2", but won't group 150 gr ABLRs at all.
As far as the great variance in the POI of different bullets. It is my experience that each bullet and especially from different manufacturers, will shoot as much as 5" at 100 yds different POI from the same weight and powder charge, just different manufacturer. Its a wonder that the 195 even hit the paper with a scope sighted in for 150 gr.
Good luck and hope you find the issue.
One more point about the "loose" stuff on the rifle. I didn't notice that you said the action/recoil lug was bedded to the stock. Depending on fit (or lack thereof), that could be a major issue on consistency.