[tobnpr]

Improper fitment of the action in the stock will cause this.
Torquing down the front action screw- in your case- appears to be causing the barrel to contact, or change location of contact, of the barrel in the forend.

In any case, front and rear screws should always be fully tightened, and 1/4 turn should never happen- it's just plain loose if you can tighten that much. The amount of torque for best accuracy is always a variable, but that's "fine tuning".

You say poi shifts (as would be expected)- but does it remain consistent with the front screw properly torqued? 30-40 in/lbs. should be about right for a wood stock without pillars.

Russian/Soviet 91/30 stocks often have terrible inletting (compared to the Finns).
Every rifle is different, some like to create a pressure point as in the pictures, others prefer to free-float. Requires some experimentation, try different methods using a piece of paper to check for locations of barrel contact, and see what provides the tightest groupings.