I FEEL YOUR PAIN!
I have a Ruger77 that shot a 1 hole or cloverleaf group, just not the same place 2 days in a row.
I have the Ruger scope mounts on it. They stink!
Sooo, I JB welded them to the receiver after solvent cleaning same, and pulled off the top rings and made a 1" lap out of drill rod and lapped those twisted and canted suckers FLATT! then the Leupold stayed steady when I installed it and gently tapped it with a screwdriver handle while looking thru it at the boresight collimator. Now instead of the 4" movement at 100 yds it stayed within 1"
Now it shoots straight. Beware those cool scope mounts with the neat adjustments, they are NEVER straight and flat. LAP THEM ALL! a 9" piece of 1" drill rod is cheap for what you get out of it. I even use it to clamp the rings pretty straight with each other while the JBWeld sets up.
Uncle Hank sez: 'Just 'cause it's new and pretty don't mean it works good"