only being able to tourq to 8"lbs is unexpected considering they say tourq to 2.5nm which is around 22"lbs.so you would figure that is what was done at factory,and if it was they would of not been able to open and close the bolt.did the wood shrink in our canadian weather,who knows.
As I said previously, I haven't seen a 1761. The 64 Anschutz rifles could experience a situation as you describe with your 1761 in which when the rear action screw was tightened beyond a certain point it interfered with the bolt. A solution to that problem was to reduce the length of the rear action screw. This would allow tightening the screw with more torque.