RE: Non-Handloader Needs Handloader Expertise!!
Well, here's just a thought.....Have you talked to the people at Superior and told them of your situation? I don't know, but perhaps they would take your gun and work with it to find what you want...but bottom line is if that was to happen, you would be shooting custom made ammo anyhow. Same as reloading. Even IF they could find a combo to your liking. My personal feeling is that most factory rifles just don't shoot sub-MOA with factory ammo. It usually takes a combination of gun tweaking and handloading to reach this goal. I would say that if your other rifles shoot sub-MOA with out-of-the-box and factory ammo use, you have been fortunate.
I guess I'd continue to try what factory ammo is left to see if you can hit your goal. Also, remember that a load that shoots well at say, 60 deg., may not shoot that well at 25 deg. There are just SOOOOO many variables in this stuff .
However, good luck with your quest....let us know how you make out.