I didnt read all of the post so excuse me if this has been said, look at the little screws in the front sight, one vertical in the top of the sight, two from each side lower than the centre of the barrel.

They are to fine tune the accuracy, especially if you have ran out of adjustment, if you cant raise or lower the sights far enough.

Loosening them allows the barrel to be pushed down by tightening the vertical screw, or loosening the vertical screw, and tightening the side screws evenly will raise the barrel.

There is left and right adjustment there too.

I think on later models the screws have been replaced by an oring, holding the barrel inside the front sight.

You may already known this.